just had a look on the web on this site
https://www.howmanyleft.co.uk/?q=triumph+vitesse
you can actually see how many its reduced by each year as well
but below are the numbers of registered cars as of 2014 so still plenty left
12/50 218
1200 934
13/60 1.3k
948 177
vitesse
VITESSE
1.4k
VITESSE 2-LITRE
17