Field Marshal 'Mad Dan' Eccles was played by Spike Milligan. He was also known as The Famous or T.F. Eccles.
Eccles was one of the show's secondary characters, but like his counterpart Bluebottle (portrayed by Peter Sellers), Eccles became extremely popular and he is regarded as epitomising the show's humour. Milligan visualised Eccles as a tall, lanky, amiable, well-meaning, but incredibly stupid teenager who often found himself involved — usually alongside Bluebottle — in one of the nefarious schemes created by arch-villain Hercules Grytpype-Thynne. In the episode "The Macreekie Rising of '74", Peter Sellers had to fill in for the role in Milligan's absence.
Eccles was often referred to as being something other than an ordinary human. Seagoon says of him "He was the nearest thing I had seen to a human being without actually being one" ("The Dreaded Batter Pudding Hurler of Bexhill-On-Sea"). In "Lurgi Strikes Britain", in a conversation about how Lurgi could easily kill every human in England, Eccles quips, "Then I'm okay, fellers!" In "The Greenslade Story", Grytpype-Thynne mentions that Eccles is colour-blind, and in "The Missing Scroll", Neddie Seagoon says of Eccles: "He was living proof that the Piltdown Skull was not a hoax." The Eccles character and his distinctive voicing were strongly influenced by Milligan's childhood love for the classic Walt Disney cartoons and specifically Disney's anthropomorphic buffoon dog character Goofy. However Eccles transcended the denseness of Goofy, being instead more like a young adult with childlike impulses, which may explain his friendship with Bluebottle.
His special talent is for taking things he hears literally, with humorous and occasionally insightful results. Thus: Seagoon (finding Eccles in a coal cellar): What are you doing here? Eccles: Everybody's gotta be somewhere. and in the same conversation (from "The Last Goon Show of All"): Seagoon: "After you deliver the coal, you're supposed to go back to the cart!", Eccles: "You mean I should let go of the sack?", Seagoon: "Yes!", Eccles: "But they said they was givin' me the sack! During an arctic expedition in Scradge", Seagoon: "Now then Dr. Eccles, any cases of frozen feet?", Eccles: "You didn't order any cases of frozen feet!"
Early cameo at the beginning of "The Mystery of the Fake Neddie Seagoons": Eccles: "What's going on here!?", Grytpype-Thynne: "Nothing.", Eccles: "Oh I'd better go then.", Bill: "The part of the mysterious stranger was played by Eccles. The rest of him was played by Rawicz and Landauer."
Probably one of the most well known moments in the Goon Show is in the episode "The Mysterious Punch-up-the-Conker" in which Bluebottle asks "What Time Is It Eccles?" and Eccles replies "Err, just a minute. I, I've got it written down 'ere on a piece of paper. A nice man wrote the time down for me this morning."
When Milligan wrote [The Idiot Weekly]], an Australian version of The Goon Show, Eccles often made appearances in the script. Eccles also possessed remarkable stupidity when dealing with physical objects; in "The Greatest Mountain in the World" he describes two sticks of dynamite as "What luck! Two big cigars and they're both lit!"