Named after Arthur Wellesley (1769-1852), 1st Duke of Wellington, the term wellington (boot) originally denoted a high boot covering the knee in front and cut away behind, later also a somewhat shorter boot worn under trousers.
This term now denotes a knee-length waterproof rubber or plastic boot, worn in wet or muddy conditions.
In British English, the noun welly, also wellie, short for wellington (boot), is used figuratively in the sense of force, power, frequently in the phrase to give it some welly and variants.
This originally referred to putting one’s foot down on the accelerator pedal in a motor vehicle.
The earliest instance that I have found is from the Conclusion of Lincolnshire Dialects (Richard Kay Publications – Boston, Lincolnshire, 1976), by George Edward Campion (1908-77):
Modern needs produce new idioms that are characteristic of present conditions. A farm labourer driving his car may be advised to ‘put yer foot down’ on the accelerator, but on a tractor he would be told to ‘give it some welly’ (Wellington boot), but both of these instructions are English and not dialectal idioms.
The following is from the Daily Mirror (London, England) of Tuesday 10th May 1977—this article by Donald Gomery is about Divina Mary Galica (born 1944), “Britain’s only Formula 1 woman driver”:
Britain’s top woman racing driver gives life ‘a bit more wellie’
Daredevil Divi is a real fast lady
The girl they call “Daredevil Divi” gave the car a bit more wellie.
In racing language, this meant she was stepping on the accelerator.
Another early instance of the phrase appeared in the column Driving topics, by Ian Johnson, in the Cheshire Observer (Chester, Cheshire, England) of Friday 17th March 1978. Under the title Rovers in the rough, Ian Johnson wrote of an event held at Stockport (Greater Manchester) during a nationwide tour organised by Leyland Cars “to teach the basics of safe off-road driving to owners, operators and potential purchasers of the Land Rover and Range Rover”:
Eyes fixed on the 45 degree drop below and the Land Rover noses downwards sending stomachs into the air . . . the engine roars against the decline and as the vehicle hits the bottom the instructor cries: “Now — give it some Wellie!”
The wheels spun, the engine roared, stomachs sank and for a few seconds the Land Rover was airborne. Bump! Back to earth and a ticking off by the Leyland Cars instructor was inevitable.
Puns on the phrase soon appeared. For example, the following from the Evening Chronicle (Newcastle upon Tyne, Northumberland) of Monday 16th July 1984 jocularly associates to give it some welly with welly throwing, i.e. a sport or pastime in which participants compete to determine who can throw a wellington boot the furthest:
Youngsters give it some welly!
The tiny tots at Ray Gray Community Centre showed how tough they are with a welly hoying contest.
One playgroup youngster set a record throw of six metres in the sponsored event to raise funds for the three times a week club, in Stotts Road, Walkergate, Newcastle.
On Friday 6th June 1986, The Liam Kelly Column, in the Evening Herald (Dublin, County Dublin, Ireland), was titled Panels will not win any prizes for their English; about “the poor grammar and loose phraseology” of the football experts on the TV panels during the World Cup, the columnist wrote the following about El Tel1, the Barcelona manager:
His masterful comment on one of Gary Lineker2’s bad misses (the one where the Purtuguese [sic] lad got goalside and got a bit of cover on and knocked Lineker’s shot away) went thus: “Yeah, the shot needed a bit more welly, that did.”
1 Terence Frederick Venables (born 1943), nicknamed El Tel, is an English former football player and manager.
2 Gary Winston Lineker (born 1960) is an English former football player and current sports broadcaster.
In Association football, i.e. soccer, welly is used specifically to denote a kick. For example, in The Guardian (London and Manchester) of Monday 12th February 1979, Charles Burgess gave an account of a match between Everton and Bristol City:
Poor Bristol City. They came and for an hour played marginally the better of what little good football there was on a difficult surface. […] The sum of the goals was greater than the whole, for the tactic most likely to succeed in the conditions was the long welly upfield, hoping to catch defenders falling about.