Success...turns out it is an 85 C plate XR3i...it's in great shape considering how long it's been standing and I mean no offence to the Brentwood built ones but I'm guessing that German built ones would be a bit more well engineered. I found it in a field and it has practically zero rust apart from a bit on the front scuttle but compared to other 'barn finds' I've seen it's pretty solid...and requires very little tlc to put her back on the road.