Tory leadership favourite's teenage activism shown on BBC's Newsnight.
The actor was reported to be on producers' "wish list" to play the royal.
A new film exploring how the Duke of York's sit down with Emily Maitlis came to be is going into production.
The BBC has made two big appointments in its current affairs team.
His response even caused Newsnight host Kirsty Wark to look on in a brief moment of disbelief.
In a heated BBC Newsnight exchange, the RMT Union leader also said he would be happy to negotiate with the Tory government.
The broadcaster announced she was leaving the BBC after 20 years to launch a new Global podcast in February.
BBC correspondent Jon Sopel has also quit the broadcaster alongside the Newsnight presenter.
The broadcaster confirmed she'd already made her final appearance on the current affairs programme.
About Newsnight
Newsnight is a daily BBC Television current affairs programme which specialises in analysis and often robust cross-examination of senior politicians. Jeremy Paxman was its main presenter for over two decades and the show is now hosted by Evan Davis, Emily Maitlis and Kirsty Wark