Mr McGregor was voiced by Richard Wilson in two episodes of The World of Peter Rabbit and Friends. The episodes are The Tale of Peter Rabbit and Benjamin Bunny and The Tale of Mrs. Tiggy-Winkle and Mr. Jeremy Fisher while Andrew Robertson voices him in this episode and one other The Tale of Samuel Whiskers or The Roly-Poly Pudding.
The books, movies and other media in the franchise, Old Mr McGregor's first name is never given. however, in "The Tale of The Flopsy Bunnies", it's revealed that his first name is "John".
In "The Tale of The Flopsy Bunnies and Mrs Tittlemouse", it's revealed that Cock Robin's surname is "Redbreast". he also made a small cameo in the Peter Rabbit movie when Tom McGregor is bird watching.
In "The Tale of The Flopsy Bunnies", it's revealed that Old Farmer McGregor's first name is "John".
In "The Tale of The Flopsy Bunnies", it's revealed that Cock Robin's surname is "Redbreast".