Joe & Jill Biden Meet Queen Elizabeth for Tea at Windsor Castle

President Biden and the First Lady met with the Queen of the U.K. this weekend to break bread and throw back some high-quality H20 -- and by that ... we mean tea and biscuits.

Joe and Jill swung by Windsor Castle Sunday for a late afternoon powwow with Queen Elizabeth II -- who was ready and waiting for them with her entire Guard of Honour standing by as well ... dressed in their red coats, and tall hats and standing as straight as ever.

When the mister and missus pulled up ... they got out greeted QE2 on a platform she was chillin' on -- and then remained upright as the crew there started playing "The Star-Spangled Banner," to which the Bidens saluted with hand over heart salutes. Liz didn't do it, though.

Anyway, after the American National Anthem was played -- Joe undertook what's considered tradition when world leaders pay a visit ... and that would be inspecting the troops. He did a lap and then circled back with Jill and the Queen, proceeding to go inside for tea time.

One last thing we should note here ... Joe remembered to do something that his predecessor infamously forgot to do, and that would be -- do NOT get ahead of the Her Majesty. Literally.

You might recall ... when Trump went for a little face time with the woman herself back in 2018 -- doing much of what Biden's doing today -- he pulled a major snafu and walked in FRONT of the Queen at one point, which is a major no-no -- and seen as poor etiquette.

Watch the clip toward the end when they start making their way in ... JB minded his manners here, and let Liz take the lead, no matter how long it took.