Clarostat Potentiometer

Scotrock

I picked up two of these Made in England Clarostat potentiometers recently, they came out of a very old guitar that was falling apart . I would be very pleased if someone could fill in some of the history of why a USA based company produced these in the UK and when. I believe Clarostat are or were owned by Honeywell and that they have been producing electronic equipment since the 1920's and they were used on Gibson guitars.
As you can see from the photos these are 1MEG LOG pots, I believe they are from the 1960's although there is no date code, the pots are stamped MADE IN ENGLAND and although it has not come out too clearly in the photos they are also stamped CLAROSTAT with a circle of V's or W's round the name. They are stamped on the side 12-2 1 MEG(OMEGA) LOG, the pot diameter is the old one inch and the shaft has been cut down but it is a 1/4 inches in diameter. I checked  there values and one is slightly below the 1 MEG and the other is slightly above.

What intrigues me about them is the design, they are very similar to other US pots such as IWC, CTS CENTRLAB etc.

Were they used on UK guitars or amps of that period and when did Honeywell stop making them in the UK and how rare are they, are they any good?