On the 15th February 1988 Red Dwarf appeared on television screens for the first time. The comedy is now celebrating its silver anniversary and thus it seems a good time for Ian Wolf to take a brief look at the worlds of sci-fi and fantasy within British comedy programming...

Many people have their own theories as to how comedy works. I tend to think that most of it works best at the extreme ends. For example, take profanity. At the one end, you can be absolutely clean and not swear at all (Harry Hill, Tim Vine) or you can be thoroughly filthy (Derek & Clive, Frankie Boyle). Let us take another possible subject: realism. At one end of the scale, you can be incredibly realistic about your subject - a gritty sitcom for example. At the other end of the scale you'll find the completely surreal and the realms of make-believe... including science fiction and fantasy. This is the area this article will focus on.

Science fiction and fantasy comedy are somewhat oddballs in terms of their place in British humour, in that the most critically respected works tend to come from the printed word. In fantasy, there are the Discworld novels of Sir Terry Pratchett. In sci-fi, the most highly regarded is probably Douglas Adams's The Hitchhiker's Guide To The Galaxy. Starting life as a radio show, its world was soon novelised, expanded and popularised in a series of best-selling books before returning to radio. To date, six books have been published, a television adaptation, numerous radio series broadcast, a film, countless items of merchandise and burgeoning cult fan followings worldwide. There's even Towel Day to celebrate the author's life.

Whilst H2G2 began on the radio, television has also proved a successful medium. We today celebrate 25 years of Red Dwarf, undoubtedly British TV's single most successful sci-fi comedy. Originally pitched as "Steptoe And Son in space", the theme and setting give it a host of classic sitcom ingredients, notably the confinement of the spaceship and the characters' ultimate predicament. Yet the inventiveness of sci-fi allows the characters to be taken out of their comfort zone for adventures within the wider 'world' established by the writers - for example, visiting a planet where time is experienced in the reverse (including the act of relieving oneself).

Indeed, the 1990s - the height of Red Dwarf's popularity - saw plenty of other fantasy and science fiction comedies broadcast on television alone.

Long-running hit Goodnight Sweetheart had Nicholas Lyndhurst's principal character travelling back and forth through time; So Haunt Me featured a Jewish ghost haunting a north London family; whilst the titlular Mulberry, played by Brush Strokes heart-throb Karl Howman, was none other than the son of the Grim Reaper himself.

Meanwhile, long-running domestic comedy 2point4 Children, whilst largely real world-based and often derided as a simple family sitcom, was in fact jam-packed with dark, supernatural elements; and the 2000s saw a successful six series of superhero sitcom My Hero going out in prime-time.

Radio, however, is still the most successful medium for both fantasy and science fiction. There are many reasons why this is. Perhaps the most obvious is the lack of budgetary constraint on production. A writer can create any setting he or she wishes, be it a spaceship, an alien planet or a parallel universe, with mere descriptive words and the odd sound effect - no expensive scenery! And, quite simply, there is no issue of struggling to achieve suitable, believably futuristic set design as, to use that old cliché, 'the images are better in your imagination'.

An early success for sci-fi on the airwaves was back in the 1950s. The Goon Show performed their own comic version of George Orwell's dystopian novel 1984, entitled 1985, in which the country was run by the totalitarian Big Brother Corporation or, as we know it, the BBC.

H2G2 may be one of the most famous audio sci-fi/fantasy comedies, but there are plenty of other very successful examples in both genres on the airwaves. For example, one branch of fantasy is 'Bangsian'; stories set partly or wholly in the afterlife. The most successful British Bangsian comedy is Radio 4's Old Harry's Game (pictured). Primarily set in Hell, the sitcom is written by and stars Andy Hamilton as Satan. It began life in 1995 and has so far broadcast seven series and several specials (the most recent during the 2012 Olympics), making it one of radio's longest running sitcoms. At the time of writing, repeats are available on iPlayer.

In recent years I have come across more audio sci-fi and fantasy radio comedies. Many of these come from BBC Radio 4 Extra, which has a special sci-fi slot called 'The 7th Dimension' (a title that was more witty back when the station was BBC Radio 7). Broadcast between 8pm and 9pm and again from midnight to 1am every day, most of the shows in this slot are dramas, but comedies are also repeated.

In the slot you can find repeats of shows including Undone, a comic drama set in a parallel version of London called Undone; Space Hacks, a sitcom about a pair of incompetent intergalactic journalists working on a space ship disguised as a hedge on Clapham Common; The Spaceship, about a team in the future trying to find alien life; and Revenge Of The Celebrity Mummies, a comedy horror set in the British Museum.

Soon after the original H2G2 radio series was broadcast, John Lloyd (the comedy producer, later creator of QI) and Andrew Marshall (creator of 2point4 Children) wrote a parody of J.R.R. Tolkien's Lord of the Rings trilogy for Radio 4 entitled Hordes Of The Things. It lasted four episodes and was only released commercially in October 2009. Interestingly, Hordes Of The Things was broadcast three months before BBC Radio 4's own highly successful drama adaptation of the original Lord of the Rings.

Villainy is something the sci-fi and fantasy comedy genres do expertly. Let us look at two recent fantasies: ElvenQuest (Radio 4) and Krod Mandoon And The Flaming Sword Of Fire (BBC Two). One thing regularly expressed by the audiences of each programme is that the best characters in these shows are the villains and their sidekicks.

In ElvenQuest, there is Lord Darkness, played by Alistair McGowan, who is typically evil but at the same time over-relaxed and constantly thinking of more cunning plans rather than getting the job done. Meanwhile his assistant Kreech (Kevin Eldon) is much more violent.

In Krod Mandoon (pictured), the villainous Chancellor Dongalor, played by Matt Lucas, kills people on a whim, with his grovelling assistant Barnabus (Alex MacQueen) un-happily going along with his every command. Some say Dongalor and Barnabus were the only good things in this latter show.

Different dynamics, but both very funny sets of characters that are able to be heightened, outside of the constraints of reality. Mind you, the fact that villains are often the best thing in such comedies is perhaps not surprising. Many of the great sitcom characters are people who are hardly pleasant. Look at Edmund Blackadder, Basil Fawlty, Alan Partridge, Bernard Black and Arnold Rimmer, to name but a few.

Sci-fi, of course, is not a genre that appeals to all. Nor indeed is fantasy; and for some reason the former appears easier to mock than the latter. Harry Venning from The Stage has perhaps hit on the reason: "What is the point in parodying the sword and sorcery genre when it is already mired in absurdity?"

Television is a harder medium for sci-fi and fantasy shows to work in. Executives seem to have fear of the genres, in no small part due to the cost of such shows' productions - a sitcom set around a family sofa is a lower-risk failure. However, a successful sci-fi programme can really pay great dividends if it works - just look at the seemingly endless merchandise related to Doctor Who, the longest-running sci-fi drama in the world. Similarly - but on a lesser scale - comedy offers us the cult behemoth that is Red Dwarf, now with 10 series under its belt and another expected to be announced this year.

It pays to be patient with sci-fi. Red Dwarf started with ratings of around 4 million back in 1988. This was rather at the time, before multi-channel television truly decimated audiences. However, the BBC stuck with it and the episode Gunmen Of The Apocalypse, which formed part of the fourth series, attracted more than 6 million viewers, picking up an International Emmy Award. Fast forward a bit, and the opening episode of Series VIII set a new BBC Two ratings record with 8 million viewers. It's a show that still works now. When Dave first revived the sitcom in 2009, the resultant Back To Earth specials attracted viewing figures the channel could scarcely have dreamed of before - the ratings graphs for the small repeats station shot up past 2 million.

Of course, not every show is given as many series as Red Dwarf to settle in before it's decided to cut the loss. Hyperdrive (pictured), the 2006 BBC Two sitcom starring Nick Frost, Kevin Eldon and a pre-fame Miranda Hart only survived two series before the axe fell, whilst the aforementioned Mulberry was cancelled because BBC bosses felt that one supernatural comedy at a time was enough - So Haunt Me was also broadcasting, but to larger audiences.

Killing a sci-fi comedy over a 'real world' one can be an easy move for commissioners - after all, if you've got to lose one show from the roster, the one sitting at the top of the costs table is the most vulnerable.

But whilst the costs and risks might be high, sci-fi and fantasy comedy will still be produced on TV from time to time. Misfits - the E4 comedy drama in which the characters have superpowers - is set to return for a further series later this year, despite not retaining a single member of the original cast.

Of course, sci-fi and fantasy are not confined and exclusive in themselves. The largely domestic 2point4 Children has already been noted, whilst Radio 4's recent much-loved Victorian spoof Bleak Expectations often breaks from the boundaries of normality (the programme has featured a flight into space, characters coming back from the dead and a tunnel made out of beef, amongst much else).

In fact, radio seems to be enjoying a little sci-fi revival of late. On top of ElvenQuest (Series 4 is on air now on Tuesdays), last year Radio 4 broadcast My First Planet, a sitcom set on a newly established space colony; and Radio 2 is now gearing up for a full series of Welcome To Our Village, Please Invade Carefully, a comedy featuring an alien takeover of Earth. Even the internet is getting involved, with the first crowd-funded British sitcom named as A Brief History Of Time Travel.

There may not be an awful lot of sci-fi on television at the moment, but it seems that radio is still offering the goods. If you're a fan of fantasy or sci-fi comedy and wondering what its future holds, just remember two simple words - DON'T PANIC!