That was usually G-BATC in Trinity House Colours at one time usually flown by Geoff Bond and crewed by Duke Guerin, others also did it of course but were relief for the dynamic duo.
It featured in a Blue Peter programme and when interviewed on camera the pilot was asked if it was dangerous, he replied not really and the bit was cut and he was told you can't say that, earlier the crew had asked for Blue Peter badges and were told that they were not handed out willy nilly, much amusement about this back at base.