The table below is from the UK oficial MOT test results in 2007 and lists the number of TR 7's (which probably includes TR7 V8 & TR 8 models) that were legally on the road in the UK that year. The year is the original date of registration.
Apparently 1971 was used as a registration date for any cars that were rebuilt/reshelled before the system was computerised, but the other pre '76 dates are probably data entry errors.
Its good to know that after 30 years almost 1% of all the 7's built are still on the road in the UK. Since in addition there would have been other cars that were off the road for one reason or another, the number is probably on the low side.
1969 3
1970 3
1971* 21
1973 5
1974 5
1975 6
1976 17
1977 70
1978 26
1979 30
1980 292
1981 296
1982 212
1983 3
Total 989
Cheers
Howard