So had a look tonight and it’s definitely the battery vent and alarm sensor wiring as above so thanks to all who replied with suggestions.
My car has a Halfords battery and the vent hadn’t been connected (a little plug was still in place) so sorted that one quickly. The alarm sensor wiring would be reconnected but it looks like the guts of the sensor are missing, hard to describe but it looks empty??
Does anyone have a picture of the sensor or a part number?
Also, the bracket is pretty rusty and I’m sure I read somewhere that stainless ones were produced by someone on here. If anyone knows where I can get one please let me know
Thanks for all your help chaps.