At Fairoaks it is accomplished by the first radio call to Info simply to say e.g. " .... Circuit detail 1 on board".
At Luton it involved a call to the tower by phone because they (grnd freq) would give a formal clearance by radio as you were taxing out - it being class D " .. cleared a VFR departure via Pirton not above 1500 feet squawk .... "
At Coventry it was necessary to fax a copy of the details and request to the tower from the "C" point.
I recall once at Chester ... many years ago, trying to book out on the radio and being sent back to the club house to telephone them, first.
Horses for courses .....
