We are also having great difficulty plotting accurate pushpins into MapPoint.

At the moment we take in Northings and Eastings data, convert to long and lat and then plot a pushpin.

The pushpin seems to be around 100m away from where it should be. We have taken on board your comments of applying the OSTN97 conversion but are sturggling to find anywhere that will help us incorporate this into our c# code.

Any help would be more than appreciated.