When I joined as an ATCA 3 in '69, my first day in the Ops room at LATCC, Frank Langthorne the senior ATCA told us we were expected to wear ties on weekday daytime duties but it wasn't 'expected' on nights or at weekends. One ATCA 2 (CW) arrived without a tie one day, was told off, and next day came in wearing a tie with a huge nude female picture on it! On nights he would wear a torn t-shirt.
Many years later at Farnborough, Ted van Dort would wear a bow tie when carrying out morning briefings for the flying display, so we all wore them too. When he went we kidded his successor Don Hickson that it was traditional that the SATCO wear a bow tie for briefings, showing him a picture of 'Mac' Pearson to prove it. Apparently he wasn't aware that Mac always wore a bow tie.