We found one on our patio today (which totally freaked me out by the way!). I am assuming it is a toad. Picture on my profile in a minute when I upload it. It was brown and spotty looking and largish. We have a brand new landscaped garden - nothing overgrown. We have a very large garden (for London) at over 100 ft. All the gardens round here are a similar size so it could have come from any of them, but none of the ones bordering us have ponds.
What is freaking me out the most is I don't know where it has gone now!!