Norfolk Broads Forum now features a 
You may be curious where it originally came from.
My immediate thought would be a car having done 100,.00 miles and then engine gets pulled out, gets refurbished or rebuilt and gets stuck into a boat.
In most cases this would appear to be the case, however, there were in fact proper marine BMC engines made for the such purposes especially with regards to the BMC 1.5 diesel.
Now there is a PDF attachment in this post, if you download it and compare it to the manufacturer plate on your BMC, you can find out some very interesting information.
This can include what vehicle it did or didn't come from and the year.
In addition, if you have a gold or silver painted BMC inboard engine? Then you may have something quite special indeed.