South Australian democracy’s unusual year continues, with Opposition Leader Stephen Marshall appointing a de facto Liberal member for Waite.

In the wake of former Liberal leader Martin Hamilton-Smith’s defection from the party to join Labor’s Cabinet, Marshall has written to voters in his seat,  offering frontbencher David Ridgway as “the Liberal representative for Waite”.

Ridgway, a member of the Legislative Council who lives in Waite, will be available to respond to concerns of the local community through a special email address, a “Waite hotline” and community meetings.

The letter to constituents from Marshall says Hamilton-Smith’s “selfish decision has understandably disappointed the electorate – particularly those who voted for a Liberal voice just 13 weeks ago”.

“I want to honour the outcome delivered in March – to have a democratically elected Liberal Member of Parliament represent your local area,” the letter says.

“To that end, I have appointed Hon David Ridgway MLC the Liberal representative for Waite.

“The majority of locals in the electorate voted for a Liberal Government and the policies my team took to the March election, so we remain committed to holding the Weatherill Government to account.”

Ridgway, the Opposition spokesman on agriculture and tourism, is from the South-East but has lived in Mitcham for more than 10 years.

He told InDaily that he was now the only Liberal MP who lived in the electorate of Waite (Hamilton-Smith has recently moved out of the seat).

He said his role was not only to listen to the concerns of the community, but to look after the local Liberal Party membership.

“There are a couple of hundred members of the party in Waite,” he said. “You can’t just ignore them – they need to feel like they are still part of the Liberal family, and they are.”

He said he hoped to recruit new members of the party, and he would be a support person for whoever was preselected as the Liberal candidate for the next election.

Ridgway chuckled at suggestions he was the new “Liberal member for Waite”.

“I’m not the member because I’m not elected – but it’s the next best thing,” he said.

He ruled out running for the seat at the 2018 election.

“I’m very comfortable being leader of the party in the Legislative Council,” he said. “I have no intentions of running for the seat of Waite.”

Hamilton-Smith, member for Waite since 1997, shocked the party in May when he agreed to join Jay Weatherill’s Cabinet, taking responsibility for Investment and Trade, Defence Industries and Veterans’ Affairs.