1. We met after Mark was in a TV documentary in the late 90s about wannabe writers and Louise sent an email to his agent saying she empathised with his plight.
2. They didn’t meet until two years later, when Louise invited Mark to her birthday meal. He sat next to a top person from the publishing world who was wearing eyeliner despite being in his 40s.
3. One of the perks of being Louise’s friend in the early noughties was her Groucho membership. This has, sadly, now lapsed.
4. Louise used to work for Eurovision winner Sandie Shaw, but her best celebrity encounter was with Justin Bieber, who gave her a hug.
5. Mark went to the same (non-private) school as Stella McCartney and once sold Neil Tennant from the Pet Shop Boys a bag of sprouts.
6. The Antidote, which is the follow up to Catch Your Death, was plotted over several meetings in a Waterloo pizza place, which is a popular hangout for middle-aged men who like snogging their secretaries.
7. 23% of emails between Mark and Louise consist of the single acronym IKR.
8. Mark used to have a hamster called Chips who once bit Louise on her left elbow.
9. It took Mark six attempts to pass his driving test, at the age of 40.
10. Their favourite TV moment of all time was when Fatima Whitbread got a cockroach stuck up her nose.
11. They both live in south London, but miles apart, and have four kids and three cats between them. All of the cats were infested with fleas at some point in 2011.
12. They use Dropbox to co-write, using a document called ‘the Master’. Whenever Mark is editing this he texts Louise to say he is ‘in the Master’. This makes him giggle because it sounds a bit rude.
13. The photo above only looks like it does because of a number of diva-esque tantrums. And Louise was quite forceful too.