If you wondered why there was a light on in my study at 2am this morning, this Glasgow gumshoe was burning the midnight oil to crack a longstanding case.
Years ago, I bought a copy of this glassplate image of George Square - only my copy didn't feature the initials 'GWW' - those of pioneering photographer George Washington Wilson.
Roll on a couple of years, and in readiness for a Lost Glasgow exhibition, I had the plate - just 2 1/2 inches by 2 1/2 inches - professionally scanned and enlarged, and it started to give up its secrets.
Looking closely at the front of the City Chambers, which opened in 1888, it was clear to see that the building work wasn't quite finished, with the grand front doors still to be fitted.
One other thing caught my eye; looking at the bottom left of the picture, I spied two kilted soldiers, bayonets fixed, marching up and down outside the North British Hotel. What were they doing there? Who was staying at the hotel who needed an armed guard?
And, there, the clues ran out...
Then, last night, in bed, flicking through Heather Lyall's 'Vanishing Glasgow', there was the same pic, only this time it was credited to George Washington Wilson, and dated 1888. And there were those two soldiers again.
At that, the penny dropped, and I remembered a passage I'd once read. I jumped out of bed (scaring my sleeping cat) and dashed through to my study, looking for one particular book - Henry Brougham Morton's 'A Hillhead Album' (1973).
Morton, born in Gibson Street, was blessed with an almost photographic memory, and, in one chapter, written in 1932, recalls the excitement as a child, in the mid-1880s, of accompanying his lawyer father into work in Glasgow.
The passage that jumped out was this:
"On the north side, plain and dignified, already elderly, stands the George Hotel (to become the North British). At its entrance are two soldiers in scarlet coats and busbies, holding rifles and bayonets fixed, on guard, for there is a High Court these days at Jail Square, and at this moment the judges are breakfasting in the Hotel."
So, no royalty, no celebrities - only Scotland's top judges tucking into a full Scottish, on expenses.
Withe case cracked, when I eventually drifted off to sleep, I enjoyed dreams of a vanished and bygone Glasgow...