When is a by-election not really a by-election? When it’s the kind of event that was held in the Bennelong electorate last Saturday.

It’s a rare occasion when a sitting member, such as the Liberal Party’s John Alexander, recontests in a by-election a seat they had previously held. There are four such occasions in Australian national politics.

Last weekend, Alexander prevailed over Labor’s high-profile candidate Kristina Keneally. The swing against him was about 4.9 per cent. On December 2, Barnaby Joyce, the former member for New England, won the seat again for the Nationals with a swing to him of 7.3 per cent.

In October 1996, Jackie Kelly achieved a swing of 5 per cent in her favour when she successfully recontested the seat of Lindsay in Sydney’s west. Alexander, Joyce and Kelly had dual citizenship problems and Kelly was also found to hold an office of profit under the crown.

Then there is the case of Irish-born Catholic Labor MP Hugh Mahon. On November 11, 1920, he was expelled from parliament on a motion moved by Nationalist Party prime minister Billy ­Hughes. Mahon was accused by Hughes of having made “seditious and disloyal utterances at a public meeting”. Mahon had railed against Britain, accusing it of “a bloody and accursed despotism” in Ireland. At the subsequent by-election in December 1920, Mahon lost to Nationalist ­George Foley after suffering a swing against him of 3.5 per cent.

The lesson seems to be that politicians with Alexander’s predicament are likelier to hold their seats and to avoid the traditional swing of about 5 per cent against the government of the day.

Sure, Mahon lost in 1920 — but the issue turned on the troubles in Ireland at a time of rampant anti-Catholic sectarianism in Australia. A century later this pheno­menon has not been erased from the Australian psyche.

Historian and former Catholic priest Paul Collins is a critic of the Vatican and the Australian Catholic hierarchy. Yet, writing in the Pearls and Irritations blog on December 12, he commented that the Royal Commission into Institutional Responses to Child Sexual Abuse “focused unduly on Catholicism and that it can’t be entirely absolved of unconscious elements of anti-Catholicism that has been the default position of Anglo-Australian culture since the 19th century”.

Mahon’s peculiar circumstances aside, the Bennelong result was in the tradition of similar by-elections in New England and Lindsay in that the former members, who happened to be part of an incumbent government, won back their seats. Except that in Bennelong there was a swing to the Labor opposition.

Viewed in this light, the Liberal Party’s victory in Bennelong was a satisfactory result. But no more than that. Sure, for the first time in years the party seemed united as self-proclaimed moderates and social conservatives worked together on a campaign that focused on political attacks against Bill Shorten, Keneally and the (political) ghost of discredited former Labor senator Sam Dastyari.

Bennelong, in Sydney’s northwest, is a seat where Malcolm Turnbull should do well. It’s not that far from his seat of Wentworth. And ethnically diverse Bennelong has a high proportion of men and women who run small businesses and send their children to non-government schools. Moreover, Alexander is a high-profile, hardworking and popular member.

Turnbull’s problems do not lie in retaining Coalition seats in Sydney or Melbourne. His challenge is to break through with an electable and simple message in Queensland, northern NSW, Western Australia and elsewhere. The Coalition’s present problems turn on the Liberal Party’s poor performance in last year’s election and elsewhere.

Last year’s campaign was very much based on the Prime Minister’s initiative. He wanted a double dissolution and a change to the Senate voting proceedings to make it harder for micro-parties to win seats. And he chose to run a “jobs and growth” campaign that failed to focus on Labor’s weaknesses. This included the failure of Kevin Rudd and Julia Gillard on border protection, which led to a situation whereby criminal people-smuggler gangs had a role in determining Australia’s immigration policy.

Also, Turnbull failed to take issue with the Opposition Leader’s links with the trade union movement and Labor’s commitment to a renewable energy target that, if implemented, was certain to drive up electricity prices.

Under Joyce’s leadership, the Nationals retained all their seats. It was the junior partner in the Coalition that saved the Turnbull government from defeat in its first term. On their part, the Liberals ran the worst campaign by an incumbent government since William McMahon’s losing effort against Gough Whitlam in 1972.

Talking to Miranda Devine on her Miranda Live radio program on Tuesday, former prime minister John Howard said he believed Turnbull could lead the Coalition at the next election, due by no later than mid-2019.

But he added that the Prime Minister “needs to understand it will be a tough fight”.

Howard added that the Turnbull government needed to “hammer” its strengths, which he cited as “economic management and national security”. The Australian economy, under Tony Abbott and Turnbull, has performed well during the past 4 ¼ years. But the real political success was Abbott’s, who achieved what many said could not be achieved: namely, stopping unlawful boat arrivals.

With the Newspoll seemingly stuck at around 53 per cent to 47 per cent in Labor’s favour, Turnbull’s task is to break through with a message capable of holding all existing Coalition seats and winning at least a few extra to give him a respectable majority.

It’s no easy task. Turnbull has yet to fully unite the Coalition’s socially conservative base behind his leadership. And he has yet to cut through with a message of the kind that, as prime minister, Howard was able to do in 1998, 2001 and 2004.

Yet, despite its showing in the opinion polls, Labor has problems too — especially in likely future by-elections.

All that’s certain is that the Coalition’s success in Bennelong and New England will soon be of little moment.