Sinclair was associated with `Challenge’, the paper of the Young Communist League Challenge newspaper in the mid- to late-1940s. He was a regular contributor to the extent that he even held an officially recognised Press Card. This had the bonus that it even permitted him to attend cinema pre-release press shows!
Sinclair was also an official Challenge delegate to the UJRF Congress in Paris in 1946, like the YCL an affiliate of the World Federation of Democratic Youth, a kind of successor to the Young Communist International that is still going strong. He was a member of the Hackney Branch of the YCL.
Mr Sinclair indicates to this site that he would love to make contact with any of his contemporaries from that time. (“Presuming them still to be living - my desire to contact them does not extend to an otherwise more extended voyage!”). E-mails to the contact address on this site for this purpose can be redirected to Mr Sinclair.