Apologies for jumping in on this thread.....
This is what I can't find a definitive answer to on the Web...
Remember it was quite legal to re-shell with an equivalent shell, new or used, until a few years ago so for anyone to establish that an illegal shell change has taken place would require the date of re-shelling to be proved beyond any doubt.
I went through this MANY years ago, as far as I can remember it was some kind of "points" system - use enough of the original parts which had different points ratings and it was all OK.
So I did it way back then, V5 shows I owned the car way back then, but all the paperwork got lost in several house moves since then but I had enough evidence to get a new V5 from DVLA (original registration date, change date to my ownership (before I re-shelled it), but no records of the points system).
After 15 plus years abandoned outside it was kind of rotten again.
So I've just rebuilt it (well, over the last three or more years) - nothing too major, just new sills, A panels and rear valance, Oh, and a bulkhead box - it was already changed to an FG front when I first rebuilt it as the damaged shell I used was missing the front and has a proper brace bar system (not the stuff currently on sale, way better - and before the IVA Police say anything it was quite legal back then, no such thing as an IVA/IVC/IV whatever...) and I'm not too worried about my bulkhead modifications as ERA did it with no issues.
My local (MOT) garage have looked at it and say they are quite happy to MOT it based on its age, modifications etc. and the paperwork I have so, apologies for the long winded ramble, but does anyone know exactly when the rules changed ???
I can't find a definitive answer on the web and don't really want to phone DVLA as the last time I tried that I got some jobsworth who refused to register an engine change size - UPWARDS.... as I couldn't produce a garage invoice (I did it myself....).
Thanks for reading.