interesting, given the screen dimensions, it would appear to be intended for PAL which aligns with the UK related labels and Ladbrooke's betting software. The betting software itself doesn't appear to match the label though, perhaps it has been flashed with different roms?
There's a phone number, perhaps you should call for "technical advice"

but be warned they appear to have moved into furniture now. The adjusted number 0151-548-7111 is still in use by:
www.dams.com
Here is the location in
streetview.
I managed to dig up this
review of a lightpen produced by them. It shows that Computapix was a subsidiary of Dams at one time.
Edit: Just noticed is says PixStik on the cartridge so looks like it should be the software for the lightpen in the above review.
Edit2: There's also a mention of it in
Hobby-Electronics-1984 [page 10 or search for pixstik].