OK, my previous post is WRONG according to Lee Holman and I have no doubt that he knows better than I do.
Here is the story according to Lee: Abbey Panels had a large fire, not unlike the one that Jaguar suffered, in the 1965 time frame. FAV and later JWA (Willment) had commitments for further production. Since Abbey was not in a position to supply the tubs, the next best provider was a company located in the same town as FAV, Tennant Panels. So that, once the reserve of Abbey Panels chassis and parts ran out, Tennant Panels produced the remaining parts. Lee says that he doesn't know the exact date at which Tennant's products began to be used, but he suspects it was circa 1966. He stated that the last, 3 or so (not an exact number) cars that were produced were done so with complete Tennant chassis, this despite the fact that Ronnie Spain makes no mention of Tennant (at least, that I can find.)
To underscore the relationship of Abbey and Tennant a look at this paragraph from a description of Bryan Wingfield's recreation of the XJ13 from
ClassicCars:
Originally intended as a road car, the recreation features a body-tub (built by Tennant Panels Ltd) mainly constructed of sheet steel, painted with twin-pack polyurethane paint and then skinned in aluminium. In order not to set up an electrolytic reaction between the aluminium and steel, the joints were bonded with aircraft adhesive and copper rivets used. Jaguar having declined to co-operate in the project by granting access to Abbey Panels’ original body buck, the recreation’s aluminium coachwork was constructed by G P Metalcraft using measurements taken from the original car and scale drawings made from photographs supplied by Jaguar historian Paul Skilleter.
Further, Lee states that 12-15 tubs that he has (my recollection and he didn't correct me) were recently produced chassis made with the tooling used "in the day" by Tennant Panels.
As to to the Willment/Safir agreement and who actually owns the moniker GT-40, that is a story for another day; but, suffice it to say that Safir cars were not built with Tennant tubs but were built on much simplified replicas of the originals produced with metal brakes, etc. and not large scale presses as the originals (Abbey or Tennant) were. Ronnie Spain says sort-of the same thing; although, the wording he uses makes it sound as though it is actually better. (?)
Assuming the validity of this account and the obsession that Lee has for making his cars part-for-part interchangable with the originals, I would see no reason why Lee Holman's cars should not or would not be accepted by the FIA, HSR, NVRS, SVRA or any other sanctioning body as continuation cars.