A couple believed to be Australia’s oldest same-sex partners – two men aged 89 and 85 – say they plan to marry in January after a half-century together but “not with any fuss” following the country’s emphatic vote to legalise same-sex marriage.

As Prime Minister Malcolm Turnbull told same-sex couples that they can start planning their weddings, John Challis, 89, and Arthur Cheeseman, 85, said the historic vote “gives us a new dignity”.

In a voluntary plebiscite, Australians voted “yes” to legalising same-sex marriage by a strong margin of 61.6 per cent to 38.4 per cent – a result that paves the way for parliament to allow same-sex weddings before Christmas.

At their home in Sydney, Mr Cheeseman and Mr Challis said they plan to marry next year – either at a nearby registry office, or at home with a civil celebrant and a cup of coffee. The couple met in 1967 at an art gallery event after they left at the same time and “just happened to smile at each other”.

“Yes we are [planning to marry],” Mr Cheeseman, a retired pharmacist, told ABC Radio.

“Just very quietly… Very simple. That’s it. I have got a 90th birthday coming up next year. We might combine it with that.”