I’m delighted to say the method worked.
Taking it all apart is the hard bit but the grey and green wire was indeed going into #12.
Scraped a tiny piece of insulation off the wire and simply dabbed it with a 12v supply. Heard the boot open and I was back in.
New battery fitted and the car runs fine. To think that up until 2008 there was a boot lock fitted for using the key. Cost cutting does create problems but then the main problem was me closing the boot without thinking.
Thanks everyone
