So to the point. I came across a great script on the Hairy Spider site that also runs a web service. I wanted to take this further so that (a) I could pass in lots of values, not just one at a time (b) it could handle the TQ-style syntax (c) not keep on hitting friendly Mr Spider's server. The code available is for the convertion from OS eastings and northings to lat/long only and I've not tried to reproduce his "proper" web service, but I do now have something that will work for my needs. I can pass in a querystring like
gr=tq709098,SW465987,tl123456,51232456,512300245600and get back something like:
[note that the last three values in the query were all for the same grid reference but in different formats, producing the same lat/long]
For me this is pretty useful. I may well extend this to take more parameters and pass out KML, but the main thing is having a means to convert the data on the fly over HTTP.
Many thanks to Hairy Spider for doing all the hard work on this. I've tested the outputs and they're very close to the OS's own tool, so good work HS!
Next thing is to use this. I'll let you know when I do, and we might also be open about making the service publicly available if that would be of assistance to anyone that might be reading this.