Thanks for the replies
Thanks for the replies good people. There have been to many theories going around( in the layman world) as to why Cardiff could not operate in foggy conditions. Being a layman I wanted to put the record straight and you have done that for me.
BTW the user name GW3XJC is my Ham ardio callsign something I have had for nearly forty years now, i am one of the few that use morse on a regular basis. Merry Xmas to all Roger Luke