In order to determine whether or not to have some part remanufactured, it is useful to know how much need there is, or may be, for the part. The numbers of each model left 'on the road' or SORNed, are available direct from DVLA now, thanks to Freedom of Information. I used to get this data for many years from SMMT, who kindly waived the charge on consideration that it was not publicised and was for club use only, but they stopped doing so a decade ago.
DVLA statistics are available from .gov, in a series of unwieldy spreadsheets presented by a choice of parameters. I chose the presentation where they are listed by date of construction, because a date might help me differentiate between, say 'Regal' as in a 1950s side valve mk V, and a 'Regal' from the 1970s, which may have a 700cc OHV engine, and in fact share almost no parts.
Each spreadsheet in fact comprises six sheets: Cars, Motorcycles, LGVs, HGVs, Buses and Others. Each make of vehicle has a row for every model, and every sub-model name, which has been found on a registration document, [as well as a row for missing model names] and a column for every year from 2019 back to 1900, plus a column for those which are undated and a totals column. Now it becomes plain why I called them unwieldy.
Add to this the fact that there are Reliants that were plainly wrongly registered, misnamed, plus add in all the Bonds with Bug in the name [there are plenty without, but we don't know that some of them are not], the fact that there are no Middlebridges anywhere, no Stevens Ciphers, no Anadols, Tempest Cars or P K Jimps - although every 'sheet' does have a big number under 'other British Vehicle' - and you can see that the figures will never be accurate.
Bear in mind too that one cannot differentiate between 'Taxed', 'SORNed for winter' and 'SORNed 20 years ago and left flattened under a pile of other stuff'.
To get the database extracts in a viewable shape meant suppressing hundreds of rows and columns and reducing the size so it's condensed enough to read across but still just big enough to see. For convenience I have missed out the occasional outlier, so the totals may be one or two 'out'. But I suspect much of this data is quite a lot 'out' before I started messing.
Oh, and in case you were wondering, there were 31 Bonds with 'Bug' as part of their name in 'CARS', 113 in 'OTHERS', 21 in MOTORCYCLES [but these were built earlier than Bugs] and none in BUSES, HGVs or LGVs . I did look.
RELIANT MODELS as listed in 2019, taxed and SORN
from the DVLA 'CARS', MOTORCYCLES', 'LGVs' and 'OTHERS' lists