‘That’s a big window, is it no’?’ he asked, ostensibly of Catherine but clearly for the benefit of Callahan. ‘Christ, the Gas Board give you a smaller time frame than that when they’re coming round to fix your boiler.’

Callahan cracked a hint of a smile, genuine amusement rather than a gesture of solidarity. Catherine detected a hint of impatience too, as if he didn’t fancy the prospect of Fleeting stringing them along. It was like he really couldn’t be bothered with this, had better things to do.

‘Well why don’t you start filling that big window in?’ Laura responded, an acidity to her patronising tone that conveyed unmistakably how unimpressed she was with his humour and with Fleeting in general.

‘Where were you?’ Catherine reiterated.

‘Sunday?’ He shrugged. ‘I was in my bed until lunchtime, close on one, maybe later. Pulled a wee durty up the toon Saturday night.’ He looked to Laura as he said this, mock conspiratorially, like she would approve or even identify. ‘Nothing to write home aboot, but your hole’s your hole. I went out and had a bit of brekky doon the boozer watching the game. That’s me till aboot six-ish. Went hame, freshened up, got changed and came here. Bar was short-staffed, too many folk away their holidays. I was helping out Mr Callahan here as a favour. Closed up about quarter to one. Does that fill your windae enough?’ he asked, giving Laura a sneer.

‘Would this “wee durty” have a name,’ Catherine asked, ‘so that we could maybe get hold of her to verify her part of your alibi?’

‘I think it was Lynn, though it might have been Lyndsay. Like I says, no’ very memorable. I mean, she was pretty dirty, but maist birds are these days. Take it all ways, like wee porn stars, so they are.’

Catherine was doing better than Laura at not rising to the bait. Maybe it was her greater experience and maybe it was that the bait wasn’t being cast for her. She wondered distantly whether to be insulted by this implication that she was too old to be worth bothering about.

‘Aye, well if it turns out she doesnae remember you either, that’s not much of an alibi, eh?’ Laura responded.

‘I’m sure she’ll remember enough. She was at my flat. She gave me her mobile number. I’ll write it doon for you,’ he told Laura. ‘Or if you give me yours, I could text you it.’

‘Which pub were you in?’ Catherine asked.

‘My local. The Raven’s Crag. You know it?’

‘Aye,’ Catherine confirmed with a small sigh. ‘It’s a popular spot for alibis. Did anybody see you there who hasn’t served a minimum of five years?’