Must say I always assumed it was not allowed because you never used to see boats there until recently.Mooring in Desborough Cut is not permitted and if I can find the relevant regulation I will post it here. While based out of Shepperton Nav Office, that is just 200m across the river, we used to slap any boats with harbourmaster's directions to move and then tow away if they failed to comply. It ain't difficult.
It would be interesting to see the "relevant regulation".
Patrol boats certainly were more active in years gone by.