Had a forum posting from someone trying to get this to work.
It was giving database access problems (GB-PVR stores its data in a database).
The real reason behind this was that the channel numbers that DABDig was being passed did not correspond with the numbers in GB-PVR. Perhaps I need to change the code to lookup against a different field. Anyway, in an attempt to work around this the savvy user had a go at using dabdig.map thinking that the problem was with the channel names.
This confused things further since it meant that DABDig was trying to use a text string to compare against an integer value in the database and hence the database lookup errors.
So - worked out a way around this by simply removing the channel numbers from the DigiGuide display and renaming the channel in DigiGuide to match the names in GB-PVR.
This worked because DABDig tries to match the channel name against the name in GB-PVR if there is no channel number present.
Meanwhile, I changed the code to make the look-ups more controllable and also for a name look-up if the "number" has non-numeric characters. This means that a simple dabdig.map entry can be used to change the name - i.e. no need to modify anything in the DigiGuide GUI and map entries only required for channels that have different names.
Will probably make another change to make configurable the field that DABDig tries to match when performing a channel number lookup which then might make it all work automatically for new users with no extra configuration required.