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I had a look at the little plate and noticed that it has the letters BM on it so think it is a benchmark, what the level line is for I'm not sure, maybe someone can enlighten.
Oanyhoo here are 2 pictures, 1 from a gatepost in Gladstone Road and the other of the station, as you can see both are the same.

They are Ordnance Survey benchmarks, and show height above sea level. More info here: https://www.ordnancesurvey.co.uk/newsro ... -benchmark

If you go to https://parallel.co.uk/os-benchmark-arc ... 81/-4.7836 you'll see a map of the 3 towns with all benchmarks highlighted - you can zoom out to see UK-wide.

Thank you Bruce
I knew the one at Gladstone Road was and had an idea about the station one but wasn't sure.
Really appreciate you confirming it for me.