The first Westminster election in which the Ecology Party put up a candidate was the Walsall North by-election held on 4th November 1976. Johnathan Tyler stood for the Ecology Party gaining 181 votes (0.48%) and coming 8th defeating only serial by-election contender Bill Boakes. The election had been caused by the resignation of John Stonehouse, elected as a Labour MP but subsequently defecting to the English National Party before resigning. In the confusion the Conservatives gained the seat and an Independent came third with the National Front also saving their deposit and coming fourth pushing the Liberal into fifth place.1

The next by-election in which Ecology stood was the one for Manchester Central held on 27th September 1979, five months after the 1979 General Election which Margaret Thatcher had won for the Conservatives. Again it was a safe Labour seat which Labour held with the same 70.7% share as at the general election. The Ecology Party candidate, John Foster, gained 129 votes, a 1.2% share, coming 5th out of 6 candidates (again defeating Bill Boakes).2 

The second by-election of the new parliament was in South West Hertfordshire held on 13th December 1979. The Conservative held the seat suffering a 7.4% swing to the Liberals. N.S.Jenkins for the Ecology Party gained 601 votes (1.6%) coming fourth out of six candidates.3

Ecology did not stand in Southend East in March, but did contest Glasgow Central on 26th June 1980 where David Mellor came sixth out of seven with 45 votes (0.6%)4

Feramanagh & S.Tyrone in April '81 saw only two candidates - a Unionist (UUP) stood against Bobby Sands who was on hunger strike in the Maze Prison and was elected as MP, dying 26 days later. The Republican movement then held the seat at the subsequent by-election in August. Ecology generally did not stand in Northern Ireland by-elections until

In the meantime in Warrington on 16th July 1981 Neil Chantrell for the Ecology Party got 219 votes (0.8%) coming 4th out of 10 candidates. This by election was notable for a safe Labour seat being challenged by the new SDP with Roy Jenkins, one of the gang-of-four defectors from Labour coming within 2000 votes of winning the seat.5

The next three mainland by-elections saw gains for the Liberals and SDP with Bill Pitt, Shirley Williams and Roy Jenkins being elected.

Croydon North West, 22nd October 1981. Ecology Party - John Foster 155 votes (0.45%).6

Crosby, 26th November 1981. Ecology Party - Richard Small 480 votes (0.83%) down from 2.8% in the 1979 General Election.7

Glasgow Hillhead, 25th March 1982. Ecology Party - Nicolette Carlaw 176 votes (0.6%). Nicolette's campaign focused on nuclear disarmament.8

Ecology did not stand in Beaconsfield, a safe Conservative seat where Labour's Tony Blair standing for the first time lost his deposit (the threshold was 12.5%). There were no Ecology candidates in the 7 of the 8 subsequent by-elections before the 1983 general election.

In Bermondsey on 23rd February 1983 George Hannah stood for Ecology, one of 16 candidates in an acrimonious by-election that saw Peter Tatchell loose the seat for Labour on a massive swing of 44.2% to the Liberals. Hannah polled only 45 votes (0.2%), possibly a record low Ecology or Green parliamentary election vote. 

After missing the first four by-elections of the new parliament Ecology stood again in Portsmouth South on 14th June 1984 with Terry Mitchell gaining 190 votes (0.5%). Thomas Layton stood as "Spare The Earth Independent Ecology" (as he had in 1982 in ) and got 50 votes. Laydon had also stood on the same ticket in Chesterfield in March.10 

The Ecology/Green party did not stand in any of the next nine mainland by-elections from June 1984 through till February 1987.

At the Greenwich by-election on 26th February 1987 Graham Bell standing for the Green Party came fourth (by a country mile) with 264 votes (0.8% of the turnout), but roundly beating all the other four fringe minor candidates (National Front came 7th just ahead of the Revolutionary Communist who had 91 supporters.

The final by-election of the 1983-87 Parliament was held in Truro on 12th March 1987. Howard Hoptrough stood for the Green Party getting 403 votes (0.8%) 

The Green Party stood in all bar one of the first seven by-elections in England and Scotland of the 1987-1992 parliament 12. They missed the Pontypridd contest in Wales in Feb'89. With the SDP in play as a fourth party occupying the space between Liberal and Labour the Greens generally came fifth but their vote share was starting to rise slightly.

Kensington 14th July 1988. Greens 5th - Philip Hobson 572 votes (2.42% +0.73 on 1987 election)

Glasgow Govan 10th November 1988. Greens 5th - George Campbell 345 votes (1.1%)

Epping Forest 18th December 1988. Greens 5th - Andrew Simms 372 votes (2.0%)

Richmond (Yorks) 23rd February 1989. Greens 5th - Robert Upshall 1473 votes (2.8%)

Vale of Glamorgan 4th May 1989. Greens 6th - M.Wakefield 971 votes (2.0%)

Glasgow Central 15th June 1989. Greens 4th - Irene Brandt 1019 votes (3.8% + 2.9 on 1987 election). The Greens finished ahead of both Liberal Democrat and Social Democrat. SNP took second place.

The Vauxhall by-election on 15th June 1989 was the first parliamentary election in which the Green Party saved their deposit (the threshold had reduced to 5% in 1985). The election, in a safe labour seat, was caused by the resignation of the sitting Labour MP Don Milligan who left the Labour Party to take up an academic post. There were 14 candidates - the most in any election in the 1980s. Henry Bewley was the Green Party candidate and polled 1,767 votes - a 6.1% share, coming in fourth place behind the Social & Liberal Democrat. There was another candidate, Dominic Allen, who stood for "The Greens" and was sponsored by a religious cult. He managed 267 votes. Despite some controversy over her selection (she was imposed against the wishes of the local Labour branch) Kate Hoey won a clear majority of 52.7%, an increase of 2.5%.13 

The next by-election was Mid-Staffordshire on 22nd March 1990, the Greens did not put up a candidate. For the remainder of 1990 Greens stood in most by-elections generally getting around 3% share, however in 1991 activity tailed of and vote shares where they did stand fell back to around 1%.

During the 1992 to 1997 parliament the Greens only stood in 2 by-elections - the first of the new parliament in Newbury on 6th May where they polled 0.6% and then not until Hemwsorth in February 1996 where they got 0.7%.