Greasby Benchmarks

Benchmarks indicate land height at points throughout Britain. They are set by Ordnance Survey and are used by architects and builders when planning new construction work. One of the main reasons is the prevention of flooding.

There are 23 properties in Greasby which have benchmarks, most are private houses. The few that can viewed in public areas are at -

Well Lane - on the garden wall of Halsall's Solicitors
126 Greasby Road - 'Oak'
154 Greasby Road - 'Salon 154'
213 Greasby Road - BP Service Station
Upton Bridge over Arrowe Brook (next to 12th Man pub)

The benchmarks are shown on Ordnance Survey maps. The figures displayed (feet on old maps, metres on modern maps) show the height of the benchmark line above Ordnance Datum Newlyn (ODN). Maps prior to 1921 showed heights to Ordnance Datum Liverpool (ODL). It took a few years until all newly published maps had moved from ODL to ODN and there are a few maps, mainly of the 1920s, which show benchmarks and spot heights to ODN but their contour lines are still to ODL. Locally, the difference between ODL and ODN is 3cm (1¼ inches) but in some parts it is much greater e.g. at Norfolk it is 46cm (18 inches).

Photos and map showing the benchmark at Well Lane.
The map has the Ordnance Survey arrowhead and "BM 92.10" which is the height of the benchmark line above Ordnance Datum Newlyn in feet. Later maps show the height as 28.078 metres.

This benchmark description in the table is " WALL E SIDE WELL LANE 4.6M N JUNC GREASBY RD" or Wall, East side of Well Lane, 4.6 metres North of the Greasby Road junction.

Benchmark at 'Oak' 126 Greasby Road

Benchmark on Upton Bridge near 12th Man pub