I think that pilings in the river is a somewhat overstatement of the feeble attempts of the Teddington liveaboards to try to circumnavigate the 'attached to land' definition of being moored.
As previously mentioned, it would only take one of the many Party boats on the Thames or a few days of rain to shift any temporary scaffold pole arrangements. They are only a foot or so from the bank.
I walked down the towpath from West Molesey to Hampton Court today and watched 8 or 10 hi-vis wearing officials, of which many appeared from a police people carrier, apply tickets to the half dozen of so sheds at Garrick's Lawn at Hampton. So they really are going for it.
Serenity Malc.