Unusual symbol

[Derek897]

Bit of an odd one, I have noticed 6 or 7 buildings in my area that have a symbol on the wall on the outside of the property, the symbol is about 4" high and 4" wide, roughly. buildings are all old, circa mid 1800's
Has anyone got any idea as to its meaning, significance ?

 

[FlyPhot]

It's a Datum Mark, or Bench Mark. Builders, engineers, surveyors use them. They are at a height above sea level (usually annotated by the mark, or in local records with a local authority) which is measured from mean sea level at Newlyn, Cornwall.

More info here: https://www.ordnancesurvey.co.uk/benchmarks/

 

[Graham W]

I think this cropped up a little while back.

 

[Derek897]

Cheers guys, much appreciated, I can rest my brain now

It's a Datum Mark, or Bench Mark. Builders, engineers, surveyors use them. They are at a height above sea level (usually annotated by the mark, or in local records with a local authority) which is measured from mean sea level at Newlyn, Cornwall.

More info here: https://www.ordnancesurvey.co.uk/benchmarks/