How and when will Prince Charles become King of England? Who was the last King of England?
Really?
When the queen dies or gives up the throne.
George V
He becomes King when his mother (Queen Elizabeth II) dies, assuming that he doesn’t end up refusing to take the throne, or do something that would make him ineligible to take the throne, such as converting to Roman Catholicism.
The last King of the United Kingdom was George VI, father of Elizabeth II, who died in 1952.
QE II is doing to Charles what Victoria did to Edward VII(prior to his actually becoming monarch) i.e.making a wastrel son cool his heels. No red boxes before Charles has an R after his first initial. Edward actually got the brass ring, remains to be seen if Charles will ever get his ass in the big chair. He could very well do the unheard of thing and stand aside so son William will get the throne. With the iron grip that Elizabeth has on the monarchy though, he could be in his 30’s before THAT big day arrives. A few of those female Windsors tend to be long-lived.
QEII won’t abdicate in favour of Charles as it’s expressly against her Coronation vows. That’s the reason, not because of “making a wastrel son cool his heels”. She believes it’s her duty to fulfil the undertaking she made that day in 1953. Anything else is bad form.
It might not make sense to more modern generations but . . . there ya go.
You see, the Lady of the Lake needs to hand him a sword…
I’m at a loss…can someone fill me in as to what this means?
Regina.
I don’t know what it means either.
Until just now I thought your name was audiolover.
Well, since the current Queen is a reptaloid alien in diguse, I don’t think she will be dying soon.
Regina = Queen
I think it’s best we don’t go down that road 
R stands for “Rex” or “Regina” – King or Queen – depending on whether the monarch currently “gloriously reigning” has XY or XX chromosome complement. Charles will be formally in Latin inscriptions Carolus III Rex – unless he chooses another throne name, as his grandfather (Prince Bertie > George VI) did.
His full name is Charles Philip Arthur George (I THINK), so there has been talk of him becoming King George VII.
Strange women lying in ponds distributing swords is no basis for a system of government. Supreme executive power derives from a mandate from the masses, not from some farcical aquatic ceremony.
Please fight my ignorance, what red boxes?
“Red Boxes” are attache cases containing government documents as they pass from minister to minister or from Prime Minister to Monarch. Used in this way it means that the Queen is keeping the duty of reading government papers and commenting on them to herself rather than delegating such work to her heir.
Thus Charles has to keep himself busy with his charities, and his various affairs. 
Well, I took ‘red boxes’ to mean post boxes which would bare the legend ‘CR III’ (Charles Regina) when Charles ascends to the throne.
Hmmmm…
If the latest rumors prove to be true, Charles could be King AND Queen…
Sorry, couldn’t help it…
To London Calling: I didn’t mean to imply that Elizabeth would abdicate for Charles, I believe privately she has very little faith in him. Victoria did, as Elizabeth does now, refuse to give the heir apparent access to the red boxes. Edward was and Charles will be fairly middle-aged before ascending to the throne, if he ever does, with no previous experience dealing with the government and its various ministers, etc. The “cooling his heels” reference alludes to the fact that both sons were/are rakes[is that too old-fashioned a word?] and as such lack the seriousness to be considered approach-worthy about state matters. Had they conducted themselves with a bit more decorum, admittedly Edward would have had to rein it in much more than Charles in this area, perhaps they could have sat in with mum on occasion. It’ll be interesting to see how it plays out over the next 25 years or so.
It’s already been pointed out in this thread that R means Rex, not Regina, for a king and it’s generally assumed that he would be called George not Charles.