In reply to Mr Fuller:
My Garmin 800 does this. Not quite as well as a dedicated walking GPS with it displayed all the time, You just change it to British grid in settings and then touch the map at your point once then again and it will give the grid reference.
This is also another way
To view your current position:-
1. Press "Menu"
2.Press the spanner (Bottom Right of Screen)
3.Press "System"
4.Press "GPS"
5. Press "View Satellites"
6. Your location will be displayed at the top of the screen.
Strange that he wants this considering you could just see where you are on the map displayed?! (I use free opensource maps).
I also only paid £150 for it on a Black Friday amazon deal last year.
Post edited at 10:59