Within an hour, Lou had sorted the letters into three neat piles lined up across both arms of her chair. Whatever her system was, it looked much better than the crumpled-up meal I’d made of things the night before when I was trying to work out where to start.

‘Talk me through it then.’

‘Well, my plan was to separate them into themes, but then I realised they were all too different so I changed tack. I’ve kept it simple, and gone with splitting them into the ones I think are going to be quite straightforward to answer and others that are going to take a bit more thought.’ She indicated two of the piles. ‘Then, in each of those groups I’ve filed them using the same concept – in order of easiest to most complex.’

‘And what’s that one then?’ I indicated the third and noticeably larger mound of letters, and saw her mouth twitch ever so slightly.

‘Oh, yes, well. These are the ones about love – difficult to live with, impossible to live without, by all accounts. When I abandoned the idea of themes I’d already sorted loads into this one, so I just kind of kept going.’ She ruffled the pile with her thumb, then gathered it up and handed it to me. ‘Everybody’s biggest problem, apparently.’

Apparently.

‘Let me know if you need any help solving that lot.’ Lou nodded at the letters in my hand and smiled wryly. ‘I’m joking, obviously.’

By the time I settled myself in my armchair with my notepad and peeled the first letter off the pile, her eyes were closed. But there was still a trace of a smile around her mouth, and I was kind of glad my sister was going to be there beside me when I had to think about love.

It never is breaking news when I fall for a woman and, hands up, I’ll be the first to admit it happens a lot. But any shine wears off me fairly quickly once they work out I’m a hopeless flirt, a terrible timekeeper, and generally a pretty poor boyfriend.

‘A woman’s heart is different, Danny,’ my mother used to say. ‘And you must be careful with it. Remember to be a gentleman and always be kind.’ And I really have tried. All my life I’ve tried to be careful with a woman’s heart, even when it hasn’t always been in my own best interests. Because when I don’t call them back or take things further, when I gently but firmly disappear from their lives, it’s not because of anything they’ve done. It’s because I wouldn’t wish me on anyone, let alone someone I was growing quite fond of.

When I was twenty-five, I got engaged after a heady two-week romance with a girl called Joanne. We swore everlasting love to each other, then her visa ran out and she had to go back to New Zealand. I proposed at the airport and never heard from her again, so maybe we’re still engaged and, come to think of it, maybe her name was Leanne.