Snakes? found one on our doorstep

Just wondering if anyone on here knows anything about Snakes?

We found this little chap on our doorstep today!

Unfortunately it appears he (or she) was trying to sneak into our house as we were going out and got shut in the front door and we didnt notice til we got back

Just wondering if anyone could tell me what it is(was)?

Sorry cr@ppy phone pics:

That's a grass snake mate