Right think I found the culprit, I noticed this morning that my google apps account had not delivered any email for a few days, it is not a address that I hand out much so normally it is just the calendar reminders that i get on it. This account is enabled through Google sync so should be pushed to the device.
I tried to manually pull them down by going into the inbox and after a few minutes got a "could not connect to the server" error. I switch of Mail in the seetings and renabled the old IMAP version of it and it pulled down the emails staright away. So I am guessing the phone went made constantly trying to pull down mail but couldn't for some reason. Battery life now seems to be back to normal.