I used to work there but left a long time ago.
Cintel themselves didn't produce CRTs, but they did use them in their flying-spot telecines as a scanning light source. The CRT was a regular replacement as it was run at pretty high eye-dazzling levels and suffered from burnout. Sorry I can't recall the actual tube as it was too long ago.
They were made by Rank Precision Tubes who were based in Sidcup, Kent IIRC.
You might want to ping dexters_lab on here as he regularly gets hold of vintage post-production equipment so he might know someone?