Some episodes were made in black and white as a result of 'the colour strike' a TV technicians' union action over a dispute.
Robin Nedwell (Dr. Duncan Warring) chose not to continue in the role for this series, to pursue other acting opportunities. However, he would return for all the subsequent ' Doctor' series, including the final, short-lived, Doctor in Charge made by the BBC in 1991.
The storyline about the doctors lusting after schoolgirls was later used in the Channel 4 programme It Was Alright in the 70s (2014) as an example of how society's attitude to acceptable sexual humour had changed over 40 years.
Doctor at Large is the only sequel of Doctor in the house that had 29 episodes in one season (or series as they call it). Doctor in charge series 1 had 27 episodes