I had the dubious honour of being on the third Shackleton trip from the September 1960 Farnborough on the 7th/8th. We didn't 'trawl up and down the channel' but trudged towards the Canary Islands, Azores and back. The sorties were 22 hours, not 24 as the takeoff was the last event one day and the return the first event of the next. We had the bomb bay fuel tank fitted, an 'enhanced' crew and flew at endurance speed which was more uncomfortable than normal! Oh, and lots of pies!
I too didn't understand why we didn't just fly down to St Mawgan and return the next day, but then we did have the intrepid (maybe most junior?) reporter aboard to scupper that idea.