Today I went to a local park in north-west London which I've been visiting quite often. There is a sign saying there are Slow Worms at that spot but I haven't seen any yet, so I decided I'll take a walk to see if I can find something! To my surprise,instead of lizards I found a pretty good sized(about 80 cm) female Natrix natrix!
It was an unexpected encounter since I haven't heard of any snakes in the area! When I cought it, it emptied its cloacal contents on my hands and it was the worst smellin Nattrix I've ever cought! I could not get rid off the stinch whole day..in fact my hands are still stinking now, as I write, no matter that I washed them 100 times and perfumed them! Next time I think I'm going to use latex gloves! 
It took me quite a long time to calm it down but it was my first Grass Snake from the UK, so I wasn't leaving without a photo!- the habitat
- Just for size comparison
Five minutes after releasing the snkae I saw another smaller one! Maybe a male but it was too quick and I coudn't get a photo! Anyway, I don't think there are a lot of them at that spot. There are too many people around..walking their dogs, children, etc. There are plans for building accomodation buildins, swimming pool and a enlarging the parking space, which is not good news! Local people are against this but I doubt it they will succeed in their protests!
Best wishes
Ilian
