Byelections are always interesting for politics addicts like me and they often assume exaggerated importance for the real politicians who see auguries of the future in the results.

It will be no coincidence that Sir John Key's resignation followed hot on the heels of a very poor showing by the National candidate in the Mt Roskill byelection of December 2016.

When political parties get voted out of office as happened to National last year, the result is often a series of byelections as MPs from the defeated party opt for retirement or to move on to greener pastures.

These byelections are particularly interesting as this is where the popularity of the new government is tested and a new opposition leader gets evaluated.

Advertisement

National has so far seen the departure of three senior MPs as a result of losing the 2017 general election but as the first two of them, Bill English and Steven Joyce, were list MPs and were simply replaced by the next name on National's Party List, no byelections were triggered.

The resignation of the former Health Minister, Dr Jonathan Coleman, an electorate MP, has resulted in a byelection next month in his seat of Northcote and this will amount to the first chance any voters will have to voice their opinions about the change of government statement by way of a vote.

Coleman had a majority of in excess of 6000 votes in 2017, and while this was 3000 down on his best effort in the 2014 election, the seat should be classed as safe and is likely to remain in National's hands.

No governing party has won a seat from an opposition party in a byelection since the 1930s so don't expect any kind of upset result.

This will not stop the pundits picking over the details of the result and, given the disproportionate political outcomes of some byelections, this could prove an interesting exercise.

A lesson that is never forgotten by my generation is an Australian byelection which took place in 1975.

This was in the Tasmanian seat of Bass in where the opposition Liberal Party candidate captured a previously safe Labor seat in a shock upset. This meant the beginning of the end for the Whitlam Labor Government which was dismissed by the governor-general six months later.

A parallel outcome that occurred via a different route can be attributed to the Northland byelection which, with the benefit of hindsight, marked the beginning of the end for the John Key/Bill English National Party Government.

Northland's National MP Mike Sabin resigned from his Northland seat without explanation in January 2015, though there had been reports of a police investigation in advance of his departure.

Steven Joyce, the National Party's campaign guru, badly mishandled the resulting byelection, with its then Transport Minister (now leader) Simon Bridges, promising to upgrade 10 old bridges.

This promise only served to underline the accusation that the electorate had been taken for granted and effectively abandoned by the National Government.

The promise then backfired even more severely when Bridges was backed into a corner and forced to promise the 10-bridge upgrade even if the National candidate was defeated.

This sequence of events obviously played into the hands of Winston Peters who was already building an image as the champion of the neglected regions, and had the advantage of having long established links to the electorate in which he grew up, and he won the byelection.

Losing a safe seat need not have been a serious problem for the National Government. National lost the safe seat of Rangitikei to Social Credit's Bruce Beetham in early 1978, but went on to win the general election that year but that was before MMP arrived and changed the rules.

Had National then made it clear to Peters that his party would be a welcome coalition partner, as all the polls were predicting, then the outcome of the general election of 2017 would have been very different.

National, however, chose to gamble that it could not only knock Peters out of Northland in the general election, but that it could, by attack, depress New Zealand First's Party vote to below the 5 per cent threshold for list seats and remove the party from Parliament altogether.

National achieved the former but not the latter. This left New Zealand First in Parliament in reduced numbers, but still as the key pivot party and very bitter with National. Here was a byelection that decided a general election.

The odds are that the Northcote byelection will not produce a result as interesting as Northland, but a low turnout or a reduced percentage for National will be a negative early verdict on Bridges.

• Mike Williams grew up in Hawke's Bay. He is CEO of the NZ Howard League and a former Labour Party president. All opinions are his and not those of Hawke's Bay Today.