They look like Washington DC plates

The first Tiger, looks like it has the 1964 WDC yellow plates.

http://imcdb.org/vehicle_3567-Sunbeam-Tiger-1964.html



The later Tiger looks like it has 1966 tags:

http://imcdb.org/vehicle_357278-Chevrolet-El-Camino-1965.html


The lettering is incorrect for both, with the characters too bold.