He has appeared in many West End musicals, including original casts of Evita, Chicago, We Will Rock You, Wicked, and Charlie and the Chocolate Factory.

[1] He has two brothers, Geoffrey and Roger, (a businessman and a musician) His father George (d 2016) established a company which pioneered technology in controlled-rate freezers, IVF and stem cell research.

With Christopher Douglas, he created the spoof actor character "Nicholas Craig", who appears in book, radio, TV and articles as well as live; including, in 2011, in Stewart Lee's At Last!

Leading roles on television include Shine on Harvey Moon, The Young Ones, Filthy Rich and Catflap, The Grimleys, King and Castle, Bonjour La Classe and Roll Over, Beethoven.

He also starred in Michael Palin's Number 27, Simon Gray's Two Lumps of Ice, Emma Tennant's Frankenstein's Baby, Blackeyes by Dennis Potter, Marcella, Cockroaches, Ratburger, and Loaded.

His first break in the theatre was understudying David Essex as Che Guevara in the original West End run of Evita.

He was a member of the original West End cast of his co-star Ben Elton's Queen musical, We Will Rock You as Pop.

[8] He featured in Doctor Who: Live touring the UK, as Vorgenson The Inter-Galactic Showman, before appearing in pantomime as Captain Hook at the Lyceum Theatre in Sheffield.

Planer went on to star as Grandpa Joe in the original production of Charlie and the Chocolate Factory, which opened in London's West End in 2013[9] for which he was nominated for an Olivier Award for best supporting actor in a musical.

Planer played Den Dennis, one of the four members of the 1980s spoof rock band Bad News, which made two albums produced by Brian May.

The Young Ones also appeared on Cliff Richard's 1986 charity rerecording of "Living Doll", which spent three weeks at number one in the UK.

He has written lyrics for "Commit No Nuisance", a music collaboration with Neil Avery ("Talk it Out", one of the songs from the album, aims to encourage male mental health awareness,) and for Swedish rocker Matts Lindblom.

Discworld Audiobooks narrated by Planer include (with number in parentheses indicating order of the book in the Discworld series): Other voice roles include the narrator of Grizzly Tales for Gruesome Kids (and the audiobook narrator for Fearsome Tales for Fiendish Kids), for which he received a BAFTA nomination, the title character in 2 series of Romuald the Reindeer, and Dr. Marmalade in an episode of SpongeBob SquarePants (alongside Young Ones co-stars Christopher Ryan and Rik Mayall).