Very little about this, as they transitioned to a WWW based service quite early.
Existing viewdata systems such as CAPITAL INFORMATION are also developing an Internet service. At present the system still operates using the more traditional videotext software but it is also converting it into WWW format.
Initial Web based service https://web.archive.org/web/19980208133530/http://www.ebs.hw.ac.uk/EDC/CapInfo/welcome.htm
Other possible sources of information