The ability to provide SRAs and the termination range were/are determined primarily by the equipment. 'Talkdowns' require precise information and therefore the shorter the wavelegth of the equipment and rotation rate of the scanner are crucial. So a Marconi 264 with a 50cm wavelength and scanner rotation of 4RPM useless......big 'blips' and very slow renewal of position. The Decca/Plessy 424, wavelength 3cm and scanner rotation of 20 odd RPM [forgotten the exact RPM...... long time ago!], excellent renewal of information enabled accurate presentation of aircraft position. The Plessey 430 with a capable scan rate of 44 RPM...... even better! The problem with the short wavelengths being the susceptibility to weather interference. So even with all the anti-clutter devices SRAs could be a problem, until the aircraft was within the last few miles of the approach.
However the technical ability of the radar was only part of the story. The real accuracy was determined by the ability of the radar operator and the guy flying the approach. So airfields such as Bristol, Luton and Leeds Bradford probably offered most success by virtue of the bad weather experienced and the frequent experience of based pilots.