the last airfield I know which offered one milers was Coventry which is no longer ATC
They used to have 1nm SRAs at Teesside until they were withdrawn 3 yrs ago leaving just the 2nm SRA. It was mainly because there is no real demand for them, and staffing means they’d rarely be available anyway (anything less than 2nm has to be done by a separate controller) it also transpired there wasn’t the requisite radar reflector in place.
2 mile SRAs don't require any setting up markers specific to a particular runway permanent or otherwise but the radar display must have some sort of permanent markers to ensure it is correctly set up.
One of the setting up markers for Farnborough's ASR10 is Canary Wharf Tower; the people installing the radar wanted us to use a gasholder in Aldershot until I pointed out it was in the process of being demolished!
On the 'old' AR1 and Watchman radars, one of the markers was the water tower at Greenham Common!