OK from the horses mouth. I am posting this with the permission of my employers as I am probably the most current pilot on this operation in the UK. The banner is not towed , it is underslung. Military helicopters do not tow vehicles or artillery pieces, relief helicopters do not tow emergency supplies and we don't tow banners. In effect our operation is no different from any of these other uses-we pick an item up, fly a set course with it and unload it at the end. We get paid for moving it in the same way that any chartered helicopter would be paid for moving a third party's item from A to B even if A and B are the same place.
Currently all banner operations in the UK are carried out under the Cabair AOC and
banner lifting exemption. If the aircraft is not a Cabair machine e.g the Cumbernauld job there is a requirement for a Cabair pilot to be on board.
Its been fun watching all the speculation!