We had some friends and neighbours round last night – a motley crew, for sure. Not the obvious crowd I’d invite to, say, a birthday party. No, a more assorted mix; some I hadn’t seen for years, some I wasn’t sure were still well disposed towards me. Some I’d never really spoken to. Some knew each other, some didn’t. Others didn’t realise they did know each other.

And I’d asked a talented pianist friend if he’d come and rouse us all to sing carols round the ‘keyboard’ (do people still have real pianos these days?). He agreed and we printed out the lyrics, and also chord sheets for anyone who wanted to bring an instrument (just me and my old guitar in the end).

There were 20 of us. None of us go to church any more (if we ever did). Yet we knew most of the words of the 21 carols off by heart; from years of schooling, choirs and Christmas carol concerts, from the year dot onwards. The tunes and the words are in the national (and to some extent international) psyche. (For Eddie Izzard fans, the loudest and most confident line of all was ‘Five gold rings’.)

The evening progressed and some tried soloing, some tried harmonising, we fooled around and laughed and scolded each other and shooshed each other; it reminded me of the homogeniser machine I used to use, as a clinical chemist, to blend chemical ingredients. That is, our individual differences and quirks and awkwardnesses gradually either disappeared or somehow slotted into place as we got on with the simple business of having fun, (unconsciously) synchronising our heart rates and breathing rates and body movements and responding to one another’s faces countless hundreds of times. I guess we all became ‘part of one another’ for a while.

The world’s most celebrated traumatologist, Dr Bessel van der Kolk, would have looked on and said something like “see how rhythmically synchronised voice and body movements, reflexly responding to one another in a common, simple, pleasurable purpose – the enjoyment of connecting – produces an overall neurological and physiological health-giving effect; lowering the stress hormone profile and enhancing the feeling of safety and relaxation”. No sophisticated trauma therapy; but probably more effective.