Helen ropes Alex in as childcare-expert and nappy-changer when she's forced to babysit her goddaughter for the day.

Friday night and Alex is at his latest temporary home - a one-bedroom rented flat of Stephens that he's having redecorated.

Alex is webchatting with his kids when they accidentally reveal that their mum has a new boyfriend. When Helen shows up the next morning with her baby god-daughter, begging Alex to be chief baby-sitter for the day, he unexpectedly agrees, suggesting they all go to the park... In fact it's a particular park which, as Helen discovers, is the park where Alex's ex-wife and kids (and therefore new boyfriend) are likely to be found. But when his plan to spy on his kids' new stepfather is rumbled, Alex relaxes and takes charge of Peta. Helen sees a new side to Alex - the responsible grown-up.

But their day of pretending to be co-parents is interrupted by a summons from Stephen to an emergency board-meeting that turns out to be a party he's arranged because he's feeling lonely.

Driving home, Helen asks Alex to move in to her spare-room. He'd love that. In fact if Helen's out tomorrow could he cook lunch at her flat for Sarah and his kids? 'There's only so many times you can go to the zoo!'

At the zoo with Sarah, Alex's kids ask him why their friend's mum saw him hiding behind a tree spying on them with his girlfriend and a baby...