I've only just seen this, 50 years late, but it was worth the wait. All the regular stalwarts are there, with the exception of Sid James and Jim Dale; but its none the worse for that. In fact its a funny, and for its time quite racy film.
Standout amongst the performances are Hattie Jacques as the 'Matron', who all the hospital staff are terrified of. However even Matron is lost for words when Oliver (played by Kenneth Williams) tells her the truth about 'the rules'. To pick one member of the cast is unfair though, as they are all good and amazingly some are still with us to this day.
The film is also a reflection of its time. Single sex wards and smoking in them as well - surely some mistake!
This is simple film, the like of which are not made today. Buy it and be entertained.