Trapdoor Bat

[psychocrawler]

Saw a biggish bat flying around both me and the top of the 4th Pitch (20m) in Trapdoor Pot on Bonfire Night for an enjoyable 10 minutes (also seen by at least one other member of the party).
Anyone seen similar in Trapdoor? Anyone any idea what species (suspect Natterer's but not an expert)?
PS First squeeze was quite tiight for an old git!

AT

 

[scurve]

I think Natterer's bats tend to roost in trees. If it was big, it could have been a Noctule:
http://en.wikipedia.org/wiki/Common_Noctule