I have just come across this thread, and I know the original question was some time ago. My late father was a flight engineer on the Comet 1, and later the Comets 2 and 4. I have got his log books, and see that between 24 April and 27 April 1954 he was part of the crew that brought G-ALYW from Colombo back to London. The remarks in his log book were "Special Cat flight after withdrawal of C of A. Max Press Alt 20,000' Max diff press 2.5psi" I also see that he was part of the crews that a month earlier had conducted the C of A test flights to G-ALYS and G-ALYW.
Referring to the OP's friend, he was also on G-ALYW with captain Rodley on part of the tour of the Queen Mother and Princess Margaret on 1 July 1953 covering the legs Kartoum - Entebbe - Salisbury, and there are entries in 1958 showing that he flew with Captain Langtry on Comet 2E's.