[MartinMarris]

Thank you everyone. For the moment I have adopted the solution suggested by Nickthedentist and purchased the converter he suggested.

I am indeed a tinkerer/builder. My ham station is entirely homebrewed from 1950s/60s designs. I'm British but lived in the USA for a long time and moved back to UK three years ago. The clock is my shack clock from America and is essentially identical to the one in the photo on the cover of ARRL's book, "How to Become a Radio Amateur" from 1968 (see attached photo). Hence the sentimental value....