EPSG:7405

WGS84 Bounds: -6.2400, 49.9400, 1.7800, 58.6700 var bounds = new OpenLayers.Bounds(-6.2400000000000002, 49.939999999999998, 1.78, 58.670000000000002);
Scope: Large and medium scale topographic mapping and engineering survey.
Last Revised: March 14, 2008
Area: UK - Great Britain mainland

OSGB36 / British National Grid + ODN height (Google it)