Postcodes are allocated to groups of about 15 houses, or single firms or single large mail receivers. David, If you search on Streetmap using the given grid ref, say NZ274459. then there is a message under the map saying "click here to convert coordinates". This converts the grid ref to latitude and longtitude and postcode DH1 5GY, and a few other things besides. If you know where the start is in a village but not the grid ref or the postcode, you can find the village, then move the pointer to the start point, then convert the coordinates. It's not unknown for grid references to be wrong - I can remember one checkpoint GR being in the North Sea.

There are a number of on-line postcode to GR (and vice versa) converters. I've used www.streetmap.co.uk a few times. If I'm given a postcode with the event details I will include it in the online and Strider listings, but I don't always have the time to do it for each event. I'm not sure how accurate a post code will be for some locations - surely it might cover a bigger area than the 100sq m of a six-figure GR?

Just working out the routes to my next two events useing the AA and free BBC on line route planner when something come up that I have been aware of for some time. I all ways use my post code as a starting point but often have to use a vague address or GR ref for the destination. The route planners are far more accurate with a Post Code. Would it be possable for event organisers to give the Post code for the start point?.