12d Model

Thanks Matthew. I have managed to get this far with a Grid Shift from British National Grid (BNG) to ETRS89 using the grid shift file (NTv2 available from https://www.ordnancesurvey.co.uk/business-and-government/help-and-support/navigation-technology/os-net/formats-for-developers.html )as you sugges...

In order to go between British National Grid and London Survey Grid a OSTN02 or OSTN15 grid shift file is used. Documentation here: https://www.ordnancesurvey.co.uk/business-and-government/help-and-support/navigation-technology/os-net/formats-for-developers.html Has anyone looked at doing this? Chee...