It’s not still done today, even on the most elaborately formal occasions, like the opening of Parliament.
Watch the Lord Chancellor in this video presenting a document to the Queen. He bows and half kneels, then walks down the steps with his back to her, bows again, and then walks off, again turning his back to her.
Here’s an entertaining account from the 18th century, of Oxford professors being introduced to King George III in 1786.
It’s by Fanny Burney, who was a lady in waiting to the Queen at the time.
On this occasion a courtier walked backwards down the steps, but the King realised that the professors would have a hard time doing it. Their antics were nonetheless amusing to Fanny Burney:
When the address was ended, the King took a paper from Lord Harcourt, and read his answer. The King reads admirably; with ease, feeling, and force, and without any hesitation. His voice is particularly full and fine. I was very much surprised by its effect. When he had done, he took off his hat, and bowed to the Chancellor and Professors, and delivered the answer to Lord Harcourt, who walking backwards descended the stairs, and presented it to the Vice-Chancellor. …
After this, the Vice-Chancellor and Professors begged for the honour of kissing the King’s hand. Lord Harcourt was again the backward messenger; and here followed a great mark of goodness in the King: he saw that nothing less than a thorough-bred old courtier, such as Lord Harcourt, could walk backwards down these steps, before himself, and in sight of so full a hall of spectators; and he therefore dispensed with being approached to his seat, and walked down himself into the area, where the Vice-Chancellor kissed his hand, and was imitated by every Professor and Doctor in the room.
Notwithstanding this considerate good-nature in his Majesty, the sight, at times, was very ridiculous. Some of the worthy collegiates, unused to such ceremonies, and unaccustomed to such a presence, the moment they bad kissed the King’s hand, turned their backs to him, and walked away as in any common room; others, attempting to do better, did still worse, by tottering and stumbling, and falling foul of those behind them; some, ashamed to kneel, took the King’s hand straight up to their mouths; others, equally off their guard, plumped down on both knees, and could hardly get up again; and many, in their confusion, fairly arose by pulling his Majesty’s hand to raise them.
As the King spoke to every one, upon Lord Harcourt’s presenting them, this ceremonial took up a good deal of time; but it was too new and diverting to appear long.