There's this stuff called Thuja - it's an ointment you can get from the chemist or maybe a health store in a little jar. I'm not sure if you can get in the UK coz I'm from Australia. But you can get it off the net.
You just apply it to the wart a couple of times a day for a week or so, and the wart will either disappear in that week, or start to shrink over the next few weeks after you stop using the ointment. I have never known it not to work, and I am constantly lending my jar to people! It's gentle, and it doesn't burn through regular skin like other wart treatments. Highly recommended