I posted about this car on LotusElan.net and got this response:-
"I wish to reassure you and all others reading this thread that the Duckworth Elan at auction at Race Retro is indeed the very car gifted to Keith Duckworth. It was invoiced by the factory in February 1968. No Colour Code or Engine No is recorded against the car, which was built up by the factory. This concurs with other cars gifted by the factory. Similarly, there is no dealer name but the first owner is recorded as D. LK. Duckworth (sic). The car was registered in Northamptonshire on 7 Jun 68.
We now come to that part of the story where I suspect some confusion has arisen. Around 2005 the car caught fire and was declared an insurance write-off. However, the fire had taken hold only around the carburetors, the remainder of the car being original. The car was then purchased back from the salvage company by Ken and Neil Myers and stripped, with the intention of a full restoration when funds permitted.
In 2016 the consignor agreed to pay for the restoration and to purchase the car. Once the car had been restored DVLA was approached for a V5, with the help and support of Club Lotus. Even the police confirmed that the identity of the car was legitimate and approved the re-registration. I do not know what more the consignor of the car, the DVLA, the police or Club Lotus could do to confirm the originality of this Elan. In addition, it would be incumbent on the auction house to satisfy themselves as to the legitimacy of this or any other car they put up for public auction. "
The consensus is that the car had a fuel fire and the insurance company wrote it off. There is some information about it on the Autosport Nostalgia forums. It was rebuilt and restored although some elements of the timeline are not clear such as how many owner's, when it was sold and bought by various parties and how severe the damage was.
Whether any of this is a concern depends on the fire of any potential owner, I guess.