Could our UK friends help me out, please?

Anna S wrote re death penalty in UK : stealing from a naval yard, throwing popcorn at the Queen Mum - important stuff like that).

There was a story on TV about some high ranking Commonwealth official who put his hand on HRH Elizabeth's back ... puportedly to guide her, or help her up steps, or some such ... the story was about the hoorahrah that "The Touch" caused in Britain!
That's all I heard.
Any truth to it and if so would someone enlighten me as to whole story?
I think I read somewhere that in earlier times it was punishable by death to touch/strike the Monarch ... is the rule still in effect? Does it have special name?
wow