[7] He explains that Brains' stutter – which he devised himself, without direction from the Andersons or scripts[7] – was a natural evolution of his characterisation: "It seems that with clever people the mind works faster than the mouth can speak.

[4] The scriptwriters solved the problem by abbreviating or cutting Brains' lines and limiting the character's appearances,[4] to the extent that by the end of Series Two, his speech impediment had been eliminated.

[13][14] In the late 1990s, before Jonathan Frakes replaced Peter Hewitt as director of the then-undeveloped live-action film adaptation, co-producer Tim Bevan approached comedian Rowan Atkinson with a view to offering him the role of Brains.

[20] A highly valued if somewhat absent-minded and socially maladroit member of IR, he designed the Thunderbird machines and other vehicles and facilities used by the organisation and its agents – indeed, much of the hardware and infrastructure.

According to Alex Pang's Thunderbirds: X-Ray Cross Sections, Jeff recruited Brains to International Rescue after he invented the 'Gravitron' artificial gravity plate for use in NASA's spacecraft.

[27] Stephen La Rivière argues that Brains is the series' "third iconic character" after Lady Penelope and Parker, and is distinctive for his "big, blue-rimmed glasses and stuttering American accent".

"[28] Jon Abbott of TV Zone magazine is critical of Brains' status as "the stammering, bespectacled genius", judging it to be one of a number of dated stereotypes inherent in the series' writing.

[30] James Gray of the website The Digital Fix considers Brains to be "easily the highlight" of film sequel Thunderbird 6 (1968), praising the "amusing" and "entertaining" scenes in which he destroys rejected prototypes of the eponymous, proposed new vehicle (displaying "a side of him we haven't seen before"), as well as the character's major role in the rescue of the Skyship One passengers.

[33] Although he questions the wisdom of giving the re-imagined Brains a son (Fermat Hackenbacker, played by Soren Fulton), he states that the scenes in which parent and child interact are "nicely done, and provide some rare warmth to proceedings".

[33] Ian Freer of Empire magazine judges Edwards' performance "uncomfortable",[34] while Glenn Erickson of DVD Talk suggests that Brains and Fermat's "'funny' stutters" are poor substitutes for "real character traits".

[37] Alastair Campbell, press secretary to former Prime Minister of the United Kingdom, Tony Blair, nicknamed Labour politician David Miliband "Brains" after the Thunderbirds character.

[42][43] Giles Wilson, writing for BBC News Magazine, praised the film's production values and suggested that it was "destined to be the memorable advert of this year", comparing it favourably to Cadbury's "Gorilla" promotions of 2007.

[42] BBC Radio 1 DJ Jo Whiley considered the advert "amazing";[44] Gerry Anderson deemed it "brilliant" and remarked that the writer should have been awarded for his joke "Good for Brains".