Just what is it!
 

Hi from a new, but fairly ancient member with a silly question. Just what purpose do the small panels with a slider placed at intervals below station platforms do? I'm sure that someone told me some, many years ago but that was in the days when I had a memory.:) :)

To Vellocette from an even older member; a silly answer;
They are fitted for mice - they don't have to dig their own holes in the new walls - and they even have front doors!
Enjoy the forum. Sometimes you can get serious answers.

Welcome Vellocette,

I had always assumed that they were reference markers to set the height of the track through the station. It's particularly critical to get the right platform height wrt the track. The track will move when it's periodically re-tamped

Hello Velocette and welcome to the forum. I believe they are known as track datum plates and as Shed Cat says they are used to indicate various measurements such as platform height above rail, distance from rail and even cant if on a bend. They will indicate if the track has crept whilst in use and can be used as a reference when carrying out tamping etc.

Many thanks for the replies guys it's been bugging me for some time.