The 54-year-old Good Morning Britain host shared he had joined the former Dynasty star for dinner at private member's club Oswald's with his Instagram fans - but not everyone was impressed.
"Another fabulously entertaining dinner last night with @joancollinsdbe," he captioned a snap of them posing together outside the venue.
He went on to describe the soap icon - who he has interviewed as part of his Life Stories TV series - as someone "whose irrepressible personality is only matched in size and splendour by her coats".
Other followers focused on a different aspect of Alexis Carrington actress Joan's appearance - how "amazing" she looks after all these years.
Her irrepressible personality is only matched in size and splendour by her coats.
However, one cheeky commenter asked: "Is that your daughter Piers?"
Piers and Joan seem to have a good friendship, having posed for snaps uploaded to social media before suggesting they both enjoy hanging out at Club 55 in Saint-Tropez.
In a photo shared by Piers last summer, Joan showed off a very healthy tan and wore a striking animal print dress and sun hat combination as she stood alongside his daughter Elise.
And the pals were also joined by Piers' Twitter nemesis Lord Sugar for a meal at the luxury French Riviera resort. Oh la la!
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