Perhaps it might be best if the DVLA stuck to first registered as the datum as opposed to introducing the term built...? In the case of my Mog, from a dull memory it was built in 1985, but not registered until 1986, perhaps sitting in a dealership for a period of time.. Though if time is taken to read into the regs, it seems first registered may be the likely datum..?
It is build date, but you can use registered date if you do not know build date - "If your vehicle was built before 1 January 1984, you can stop paying vehicle tax from 1 April 2024. If you do not know when your vehicle was built, but it was registered before 8 January 1984, you do not need to pay vehicle tax from 1 April 2024."
As for where the line might be drawn in terms of modification relative to requirement to present for MOT or not.... With matching numbers yet tubular shockers all round, my old Mog is not as original, having been "restored" at circa 8k miles circa Y2K, which also included a colour change and stainless steel fixings and trim utilised in many areas...Hmm..?
From that which I read, it seems down to the registered keeper to make the decision as to whether the machine is reasonably original....?
Thinking back to the High Court case of Old Number One.... (-:
They do offer guidance -
https://www.gov.uk/government/publi...-classic-vehicles-mot-exemption-criteria
