we have a gardener for one morning a week. He is really interested and knowledgeable about all kinds of wildlife. He knows that I studied zoology at university and share his interest, and that I have recently discovered a love of photography so when he found this little creature clinging to a wall he came and called me to have a look.
Its body was about 7mm long and each leg was about 3cm.
Neither of us knew what it was, but I have managed to find out that it is a kind of harvestman which like spiders is an arachnid. It looks different to other harvestmen because when it rests it spreads its eight legs flat and its pedipalps (the bits that look like legs at the front) are forked.
When they feel threatened they shed one of their legs which carries on twitching and moving on the ground to create a diversion while it escapes. Counting its legs it looks like this one must have had a fright recently!
Thanks for the background information.