The game is among collectors known as "cardiogram". The game originally came from a seller from England and it carries the CGL logo. CGL stands for Computer Games Limited. CGL was a company based in London and it was the distributor of Game&Watch and other handheld brands in the UK.

Update January 28th 2018: The Plessey Company plc was a British-based international electronics, defence and telecommunications company, originated in 1917. In 1989, it was taken over by a consortium formed by GEC and Siemens which split the assets of the Plessey group.
Source and more information about Plessey: Wiki