I've finally identified the exact model of this TK-41 type Marconi colour camera. It is a Marconi BD848 IO colour camera just like the ones used in the BBC colour experiments in the late 50s. A picture of the BD848 can be seen on the TV Camera Museum site on this page
http://www.tvcameramuseum.org/marconi/bd848/bd848p1.htm . The resemblance is pretty much exact except there is vent holes in the viewfinder on the medical camera.