Old-Duffer
Well said.
Re "I challenge anybody on this forum to outline an alternative system which would fit the Commonwealth model and, importantly, to nominate a candidate for the role (Mandela's too old)."
I think the hard part will be finding someone who is not going to lie (a min of 2 US Presidents + many politicians), get caught out or get caught in compromising situations (at least 1 recent US President + many politicians), or have the back bone like the current Queen.
Or have the drawing power that helps the British tourist industry.