Both are fathers with expertise in children’s issues, which led to them backing the Duchess of Cambridge’s early childhood project, the Royal Foundation Centre For Early Childhood, which hopes to transform the lives of generations of children.

And their theatre version of Operation Ouch!, Live On Stage – Not For The Squeamish, has just returned to the West End for the second time on selected days over the season. 

An endoscope will look inside Xand’s head (“We’re not going up his bottom… not enjoyable for him or the audience”, according to his brother) while Chris will be sawn non-surgically in half to examine his innards in the oldest magic trick in the business.

“We won’t be getting children up on stage because of Covid rules, but there will still be a lot of audience interaction. They can ask us anything they want: all the disgusting, rude things that children want to know about – such as whale poo,” says Chris.

Somehow the doctors have to fit their ongoing day (and sometimes night) jobs around this hectic schedule. Chris works at the Hospital For Tropical Diseases, part of London’s University College Hospital, while Xand’s work is primarily academic as the Helen Hamlyn senior fellow at Fordham University in New York. Until recently he was based in there but has now come back to live in his hometown of London and work remotely.

But at least the twins will be getting Christmas Day and Boxing Day off. They’re looking forward to spending the break as an extended family at the West London house of their parents Anthony and Kit, along with Chris’s wife Dinah and their daughters Lyra, four, and Sasha, one.  

“We have all had Covid and are triple-vaccinated. Of everyone, I got the most ill – I got heart arrhythmia so I ended up in hospital. It took me about a year to recover, but I’m all fixed now and not on any pills. I’m in good shape,” says Xand, who caught the virus last year while he and Chris were making a programme about the pandemic. Doctors had to stop and start his heart to regularise the rhythm.