Datapen Microtechnology Ltd
From CPCWiki - THE Amstrad CPC encyclopedia!
Datapen Microtechnology Ltd is a british company. Their first product has been a lightpen for the ZX Spectrum, their lightpen was called Datapen, hence the company name.
The Datapen (light-pen) was also available for CPC.
According to Hwlist from retroisle the also made a "Trackerball/Rollerball" for CPC.