The Essex-born act­ress, who recently disclosed that she used to “love” snorting cocaine, says she was left cringing in embarrassment after delivering a “stumbling, nauseating” speech in front of Her Majesty at the annual society event.

“It was a strange experience because the Queen invited me there and I ended up sitting between  Sheikh [Mohammed] of Dubai and the Duke of Edinburgh,” reveals the 63-year-old, who had previously turned down an invitation to dinner at Buckingham Palace because she was away filming.

“The Queen invited us all outside to watch the racing. I think it was just a gesture to say, ‘It’s OK. We’re cool about the film [The Queen]’.

“As I left I stood up and made this stumbling, nauseating little speech about what an honour it had all been and I went on and on and made a complete and utter ****ing pleb of myself.

“But,” adds Dame Helen gratefully, “she took it on board very graciously and then off I went – to have a large glass of wine and recover.”