MW36-24 has a tetrode gun and the MW36-44 has the Philips pentode gun.
All Mullard 17" 70* CRTs including the metal cone MW43-43 have pentode guns.
Looking circuits of early Cossor 17" TVs such as the model 933 of 1953 the CRTs are drawn as having tetrode guns. The 171K and 172K are similar except for the possibility having been sourced from different suppliers. One might have been Electronic Tubes Ltd. ETEL.
https://www.gracesguide.co.uk/Electronic_Tubes
DFWB.