Ten series in, and Heidi Thomas has for some time been confident enough to dispense with the stunts and the gimmicks for the Call the Midwife Christmas Special (BBC One). No bombs or epidemics in 1966 Poplar; instead, just a Boxing Day wedding and an unseasonal pile-up of pregnant mothers (“what do you suppose was going on in March?” ponders one of the midwives, to be met by a sea of knowing looks).

For perhaps the first time, though, 90 minutes felt a bit long. The storytelling was a little baggier, the longueurs a touch more indulgent. Even Vanessa Redgrave’s narration sounded a little frailer and lighter on conviction. But for the most part, Thomas’s touch was sure, hitting sweet rather saccharine, beginning where most Christmas specials might bow out (with a super-cute school nativity) and as always lacing the enveloping warmth with social commentary.

In this case the latter came courtesy of Anita Page (Rosie Day), a heroin-addicted young mother who passed on the condition to her newborn baby and found her maternal instinct in the nick of time; the visiting Mother Mildred (Miriam Margolyes, once again offering a warmer riff on her deathlessly imperious Lady Whiteadder) assessed, with uncanny foresight, that “it is a new challenge in this country and it will become a scourge.” She also had a startling revelation for Patrick and Shelagh Turner (Stephen McGann and Laura Main) – that their adopted daughter Angela had also been born an addict. 

Just Say No(nnatus), kids. This was tough, unflinching stuff, slightly undermined by the strangeness of Anita’s domestic set-up, surrounded by comical goons whose hardman credentials were knowingly undermined when one of them squealed about having TCP applied to a wound.