There is now a suggested UK standard for how it should be done for new installations that has gone into the ETCS standard too.
(Positioning using ETCS balise as per Thameslink/700s*, similar to TASS for tilt on WCML) this hasn't stopped some recently arriving rolling stock from very new to the UK manufacturers not using the suggested method...
*also includes auto door opening in the core when the wheels stop turning and the train is in the right place
The original RFID installation was 18 years ago (southern 377s (no GPS in Victoria P9 upwards!) but that was a proprietary RFID system (Hima-Sella TracklinkII), several operators went for TracklinkIII: FCC for 377s/387s on thameslink, SWT for 458s etc retrofit on the Windsor line and LU as an interim measure on SSR (S Stock).
Most of the implementation with balises also include Correct Side Door Enabling (CSDE).
Longer term as all stock will have ETCS equipment this will be cheaper as it will be software on train + install 10year lifespan balises in the correct place on the tracks.
Also look for Automatic Brake and Door Opening (ABDO) on the SWR 701 taking the technology to a new step.