It was the food equivalent of a rock superstar's secret gig in a local North London boozer.
In-N-Out Burger, the LA burger chain founded in 1948, adored by foodies like Gordon Ramsey, Julia Child and Anthony Bourdain, made a special guest appearance across the Atlantic, for less than five hours, opening a pop-up shop in an unassuming Hendon cafe.
Its arrival was announcing by an unassuming newspaper advert and a green sign posted on the door of the Florence Cafe in the quiet north west London suburb's unassuming high street.
It said the cafe would be closed for a "special event" with In-N-Out Burgers serving between 11-3pm.
Twitter users expressed their bewilderment at the choice of location, at the far end of the Northern Line, and whether the pop-up was genuine.
Those venturing for a Tuesday lunch found a makeshift sign in the window of the cafe, but a genuine menu board was installed, with choices of burger or cheeseburger, served with salt and vinegar crisps - though the buns were reportedly a very British Warburtons.
Blogger Burger Addict reported customer service reps for the company in the US had confirmed the pop-up was official.
He said: "The real test to see if the quality had transfered across the pond...Booya it had. It was as I remembered it State-side, incredibly flavoursome and juicy with the kick of mustard due to the animal style cooking.
"Why Hendon? They want people to have to work a bit to get the burgers he said, not impossible to get to but when you think of the numbers and random passers by who would have queued I think they are doing the right thing."Suggest a correction