help - cat has run off!

[notsoyoungnstupid]

Hello - help, I feel so stupid. We let our rescue cat out for the first time this evening, after having her in for 10 weeks. I'd read that she'd not stray too far and come back in half an hour if we hadn't fed her. She legged it out the front gate and up the road and hasn't been back for hours. My daughter is distraught and I wish we had waited to let her out. The whole place will be crawling with builders tomorrow dismantling the roof - I wanted to let her out before they came otherwise it would be another 6 weeks at least until the roof was done and I felt mean about keeping her in so long. She's a lovely affectionate cat, but she was originally a stray rescued by cats protection. We've been up and down the road calling her, but I can't see a sign of her. We're in London on a quiet road, but with an evil traffic filled road about 200 yards away.
She's chipped and has a collar. Any advice please?

thanks potap - we've done the litter sprinkling thing and we're on the first floor so I don't think she'd be able to get in the window if we left it open,even if she managed to get on the scaffolding. She seemed fine with going out of the cat flap - I don't know if she'll be able to work out how to go back in again, but I've set it to let her in and then not let her out.

:-(

hi op i know this is an old thread but wanted to comment on something that helped me.
I took in a relatives cat who passed, the cat was in my house for around 5 days but got out and i was scared he wouldnt come back.
I got a blanket with his scent on and waved it outside were my cat used to go out, then i left the blanket on a washing line to blow in the wind, my cat came back. try it if he is still lost

I've just realised I never posted back!!!
Cat came back after 36 hours. We saw her in our neighbour's garden looking very happy with herself and DD was in tears lobbing bits of salmon (my dinner) over the fence begging her to come back. A couple of hours later she sauntered in looking for food. Cats. We do love her, she spends most of her time outside even in the recent cold and rain but comes in around 7pm for food and a good old cuddle and story time in DDs bed.

Have ceased worrying about her. She's an alleycat with a heart of gold but will do as she pleases and we will just have to get used to it. Thanks for all your help.