Ndtyhij

In The Laundry Files, the actual HQ of The Laundry is the perpetually under (re-)construction Dansey House. According to the author, Charles Stross, it's located

[...] hypothetically, somewhere between Leicester Square and Charing Cross: the legacy of wartime spillover from Westminster [...]

There's not that much between Leicester Square and Charing Cross — mainly the National Gallery.

Can we deduce the location of Dansey House any further? And closely related, is there a real-world inspiration for it?

It's said in as couple of books that Dansey house is in an Edwardian building. Based only on that and the location there is a large Edwardian on the Charing Cross side of Leicester Square itself, in real life it's home to the 5-Star Radisson Blu Edwardian Hotel, but it looks to have space for Mahogany Row. There is also a continuous terrace of other period edifices that extends down Irving St and would provide enough total volume to accommodate the whole bloated department.

I always assumed that although the location is wrong by about a mile, it was based on 54 Broadway, the secret headquarters of the SIS during WW2. I've been to meetings there when the London Underground were using it as overflow office space in the 90's, and it feels right for it. Has secret entrances and so on.

Edited to add my (quite tenuous) reasoning.

In the atrocity archives, Not long after Mo is recruited, Bob takes her for a drink at Wagamamas, and explains some laundry history. 'Back in the second world war, they were based in a chinese laundry in Soho, I think. They got Dansey House when the Dustbin's new skyscraper was commissioned'. It seems that the Laundry have had Dansey house for many decades, so it's the prior property of an organisation that moved into a skyscraper in the 50's, 60's or at a push 70's.

I don't know who is nicknamed 'the dustbin' , but it's clear from other references that it's another intelligence or related organisation, because they have training courses and liason meetings there.

The only UK intelligence agency I can think of who moved into a building that might have been described as a skyscraper in that time is MI6, who moved into Century house in about '64. Century house isn't a skyscraper, but at 22 floors it does tower over it's low-rise surroundings. It might have been called one once. MI6 vacated 54 broadway when they moved into century house.

All pretty thin when I think about it. I don't know who 'the dustbin' is, although it may refer to the quote about 'Whitehalls dustbin of embarrassing discards'

And it's all just post hoc justification. I found out that 54 Broadway, a building I had worked in, was a former spy headquarters not long after reading the atrocity archives and somehow it rang bells.