On Saturday afternoon as I was walking my dog, minding my own business, a small insect landed on my arm, put its proboscis into the skin and started sucking my blood. I could see it was not a mosquito, but definitely a bug, with wings folded under wing-cases, and it was kind of dull in colour, maybe mottled dark grey. The pain got too much and I knocked the insect off. Now the area surrounding the bite is hot and itchy. A friend told me it could have been an assassin bug- is this right? Do they usually live in the UK, or is this something that has moved north due to the warmer climate? I have not seen these insects before. I was walking across a golf course, near a drainage ditch with a bit of water, and not far from woodland. Unfortunately I did not have a container to catch the specimen. It was no more than 10 mm long.
The bugs normally responsible for biting people are anthocorids - they've bitten me on odd occasions. It would a good idea to find pictures of them (e.g. Anthocoris nemorum, which is common) on the internet and see if they look likely culprits