Looks like a C to me. Lathes.co.uk says 'A (gearbox and power feeds), B (changewheels with power feeds) and C (changewheels and hand-cross feed) ' and that accords with my own experience.
The leadscrew engagement handle also tells you something about the age (black plastic on the much later models), as does the position of the backgear change handle (top of the headstock on much later models). The thickness of the base of the cross-slide indicates whether the lathe is 4.5inch or 5inch centre height.
Serial number (often at the right hand end of the bed, stamped into the front bed way, should also tell you (at least on the underdrive machines, but I imagine on the others too).
There are different bed lengths.
Marcus