Just a word of caution, a huge number of telesales databases use Yell as their "source".... you'll get a huge number of sales queries of people trying to sell you stuff. We get up to 3 a day!
No one really uses Yell anymore BUT for websites I've built the online directory, where you can add your link to your advert works really really really well, so long as you have a good website.
Hope that helps,
Joel