Marie and Jackman both leaned forward. ‘What kind of luck?’ Jackman said.

‘Oh, the best. What do we love more than anything, my dears? We love blood!’

‘Blood? Why? Whose?’ asked Jackman in surprise.

‘His, for sure. Because it wasn’t hers — that was the first thing we checked. And it was miniscule, just a tiny smear, but it didn’t escape the eagle eyes of our Cardiff. She found it on the outside of the wardrobe door. I’d say he caught his finger or thumb on something sharp and tore a tiny hole in his glove. Maybe it was on one of the strands of the tripwire as he twisted it taut. He would never have seen it in the dark or by torchlight.’

Jackman laughed. ‘That’s massive, Rory! When we get a suspect, we’ll be able to prove whether or not he was in Nan’s house. Say thank you to Cardiff for us.’

‘Oh, I shan’t do that. It’ll give her ideas above her station. Anyway, there’s more to come.’ He drained his beaker of coffee. ‘We now think that he managed to wake the old lady, but without startling her. We have no idea how. Now, what happens if an elderly person is roused from sleep? They inevitably want to pass water, and we know she took furosemide, a diuretic tablet. So, half asleep, she wanders off to the bathroom. Meanwhile, Spiderman goes downstairs. And here is where I stray into hypothesis . . .’

‘We do a lot of that, Rory,’ said Marie, ‘and it’s often right, so hit us with your theory.’

‘All right. See if you agree. Bear in mind, the clothes disappeared from the house along with Spiderman, so it’s reasonable to suggest he was wearing them, yes?’

They nodded.

‘Now, your man gets through tiny spaces, so he’s wiry and lithe. Nan’s deceased husband, whose clothes she couldn’t part with, was heavily built. So, why steal clothes that didn’t fit?’

‘He put them on over his own clothes for effect,’ Marie said.

Rory beamed at her. ‘My thoughts precisely.’

‘Coat hangers,’ sighed Jackman. ‘They bothered me from the start. He deliberately picked a distinctive jacket and matching trousers because he wanted to look like the dead husband.’

‘Exactly! There’s a street light right outside her front door. He dressed up in the husband’s clothes and showed himself to the old lady. Woozy from her sleeping tablets, she either took a step forward to see better or started to go down the stairs. We’ll probably never know which it was. Suffice it to say, she fell to her death.’

‘Lizzie Coupland told me that Nan often talked about “seeing” her Henry around the house,’ Marie said. ‘She talked to him all the time, apparently, as if he was still with her. So, if she was half asleep, it’s perfectly reasonable for her to think she was seeing her husband.’

‘Calculating bastard,’ growled Jackman.

‘Absolutely. Anyway, moving on,’ Rory said. ‘He then spent some considerable time looking for her photo album, which he found upstairs in a bedside cabinet. We know that because of what had been disturbed. She was a very tidy person, and he left the room in some disarray. And we know he took his time because he left a faint footprint in her blood in the hallway. Since it came from a small wound caused by the fall, it would have taken some time to seep into the spot where he trod in it. He tore the relevant page from the album and left the book in the lounge, where your Gary found it. And then he slipped out into the night. End of story.’