Ah, see, I went to a nice studio in Camden, who said they knew the format, had done it before. I took them home, measured them, and saw they were wrong. Emailed, got mailed new pics. Great.
Then I sent the pics to the embassy, and got them sent back. I think the size of my head was wrong?
At any rate, I went to a nice local photo place, that mostly did developing, and brought the guidelines with me. They did the pictures quickly and cheaply.
I do keep meaning to get a British passport, just for the sake of it. I'm certainly eligible for one. But to do it, I think I have to send in my Canadian passport (while they do the admin), and the idea of that just gives me the wiggins.