Thank you both. Perhaps not such a simple question then!
I am aware (and having checked with the reference) that landing could technically be done AS a formation with a land after clearance which leaves it up to the pilot following to separate, unless of course MATSp2 or other dictates a minimum for controllers to issue such clearance. It does not however tie in with explicitly clearing a formation (as a formation) to land.
The reference for take off would deem it to be not allowed, however I believe that aircraft in formation are considered to be 1 unit for the purposes of seperation as long as they remain within a limit (I can't remember it now... same level and 3 miles is it? seems large). I do not know if this applies on the ground for take off and landing purposes also.
It is interested that you both give different answers - hopefully more can contribute.