Once the initial wave of shock passes, I straighten up and force myself to think about things rationally. I mean, that suitcase is so hideously noisy that no thief in his right mind would want to drag it for any distance. And who wants a load of old clothes, anyway? (Apart from me, obviously.)

First, because of the noise of my rickety case, I’m guessing the man wouldn’t have gone far. He’d probably nip down one of the residential side streets, out of sight, and find a quiet place to rummage through the contents of the bag, to see if there was anything in there worth keeping. And when he found that there wasn’t, I reassure myself, he’d dump it and walk away.

Guided by instinct and a bit of local knowledge, I head to Castlehaven Road, where there’s a large triangle of overgrown grass surrounded by wooden benches, known optimistically as The Gardens, which is usually deserted.

Today it’s busy. Circling each other on skateboards are three boys – for a hopeful but disappointing moment it sounds just like the wheels on my case. On one of the benches, two tanned and amiable drunks are making philosophical conversation through the medium of Carlsberg Special Brew lager.

The kids watch me suspiciously as I walk around the perimeter of the garden, eyes alert, holding firmly on to my handbag and visualising my scattered clothing fluttering in the long grass like injured birds (this is how sure I am I’ll find them).

But I don’t find them. On the path, the boys circle like sharks. I leave the gardens and walk slowly back to Chalk Farm Road, knowing I should keep on looking but also knowing in my heart how pointless it could be. The guy with my case could have headed straight for the towpath, or for the car park in the superstore, or down any of the other side streets, or he could have gone straight home. I think about my pathetic gratitude as he’d held my case for me while I triumphantly dashed onto the bus to hand the old lady her money back. That’s what you get for helping someone out, I reflect bitterly.

Back on Chalk Farm Road I look across towards the market. Miraculously, I suddenly see that pink shirt as he reappears right at the entrance to the Stables with my suitcase. ‘Hey!’ I yell. ‘Excuse me!’

‘Hey!’

We’re shouting across the traffic and waving our arms at each other.

‘Wait there!’ I’m dashing across in my pencil skirt, dodging cars – this is the way to cross a road in London: assertively. ‘My bag!’ I say warmly and with happy relief until I see he’s holding a small shaggy brown dog on a lead. I feel a familiar rush of fear and I keep a distance between us. I’ve got a thing about dogs.