Back in the 60s plugging into a VOX, I would imagine he was playing through Celestion Alnicos. Assuming he's playing through these now (and that KCP looks like his set up on the Farewell Tour DVD), I wonder why the change to Jensens? Simple preference?
Andrew: I do not know if Hank Marvin has his amplifier equipped with the Jensen Alnico speakers on the last tour. I suspect that the engineers were looking for a vintage Fender sound and a way to cut on overall cost. While this was likely not a concern for an amplifier for Marvin, it is a good practical approach.
The high Jensen rating may make it more appealing to some players with less breakup across the range of the speaker. Having said that, I do not think that for a classic 1960s Marvin tone that the Jensens could top the Celestion Blues.
Life, as with music, often requires one to let go of the melody and listen to the rhythm