Ooh I don't think so. It has a blue light to show it's on but its not illuminated when engine is off. We're usually pretty good at removing/turning off anything we can but this time forgot

This is long one as it has stumped us.
We bought Bruce (N reg, 2L diesel) about 3 years ago and we have had to change the starter battery twice in that time (and leisure battery 3 times - but that could have been poor maintenance on our part)
We haven't had many problems recently and we took him for ...