I fear your memory is at fault. We spent a year at Hartford in 2008/9 when there were no pontoon moorings other than for sales plus a few boats moored at the eastern end. However the floating caravans at the western end and the two sets of floating lodges at the eastern end were then in place.
Tingdene took over in 2016 and installed the floating walkway on the riverside of the marina and the first of the long fingers now called D pontoon which is where we have moored since 2021.
The floating caravans are probably sitting in time expired floats and certainly the steelwork of one broken up earlier this year would seem to prove that. Tingdene gave notice 3 or 4 years ago to the caravans that their pontoon walkway required replacement and that they, the caravan owners were responsible for payment. Nothing happened except a huge increase in their fees until this winter when several of them broke free in high winds.
This forced Tingdene to replace about half of the pontoons, to a new layout which may be why you thought they had increased. 3 if the caravans were re-moored to the new pontoon, one was broken up and one towed downstream to Wyton Moorings. There is now a lot of empty pontoon but Tingdene haven't said what they intend to do with it.
In the last few years Tingdene have gone from one long finger pontoon with around 60 moorings to four although not full occupancy. They have given us a proper carpark and surfaced the access road but at the same time closed the chandlery and the onsite mechanic has left due to rent increases.
One thing the moorers at Farndon could expect is the sale of diesel at 60/40 only to bring them in line with their other marinas.