Oh god you're so right. Or Caleb will find it and kidnap Gabby and lock her in (a) a car boot and then (b) a barn, crazed with jealousy about his gay lover Nicky having the jiggy sofa lurve with the siren temptress.
However - here's the twist - Caleb has thrown the positive test back into the bin in disgust, prior to kidnapping Gabby, and while he's off doing his dastardly deeds Billy finds it and thinks it's Dawn's.
Billy paces about a bit in a fever of emotion and eventually puts it on the table on top of Kim's laptop before rushing off to find Dawn, only for Will to wander in and find it. Will gawps at the test, and then glances at the laptop and sees an open page about IVF, because Kim's been on Mumsnet again and clicked on one of the interminable advert links by accident before being called away to the champagne cupboard.
It's all real to me, like I was there.