Question from Clemmie - Death of George, Duke of Clarence

I am curious about the execution of Edward IV's brother (George, Duke of Clarence) . Legend has it he was drowned in Malmsey wine. It seems the rumour circulated shortly after his death; Shakespeare then said the same in his play (although I am aware of how very little historical his plays can be) Since there is no proof about how George actually died, does anyone think the wine option is likely? I actually do not know what to think. It seems like an odd way to die, and a rather complicated and expensive choice to execute a convicted traitor (even though he was brother to the king). Second question, if the Malmsey is actually not how George died, how was he actually killed? We are of course only making hypothesis. I could only find he was "executed privately". What is the most likely way for it to have been carried out (for it to be quick and private)? Beheaded? Stabbed? Strangled? I would love to find out what truly happened to him.