I am using Easy Trails software on an iPhone to output a gpx file of a walk. When I import the file (import vector layer) to QGIS, into a project with OSGB information and the correct CRS for OSGB data, the imported track appears well to the West and South of where it should be. I have tried changing the CRS in both layers, tried changing the project CRS, enabled and disabled on the fly projection but no combination of what I try will get the track into the right place. I feel I must be doing something fundamentally wrong but cannot work out what it might be. Am I missing some vital step out?
Have you tried WGS 84 for the GPX data? It is EPSG code 4326. You'll need on the fly projection turned on unless your OSGB data is also WGS 84.
You can also check by exporting to CSV instead of GPX, then look in the text file. If the coordinates are in degrees then you're probably dealing with WGS84.
Edit: GPX is always WGS 84. I was thinking of Garmin's GDB format, which can be any number of other projections. So you'll need to set the GPX to WGS84, turn on on the fly projection. If you're still not lining up you have the wrong projection defined for your OSGB data.