It was on a family holiday, 1200km north of Perth, earlier this year that Mitchell Marsh's plan to make an unforgettable mark on the Ashes was hatched.

The shoulder injury that had cut short his tour of India in the autumn threatened to again leave him on the outer of an Australian team in which he had never really established himself as a permanent fixture.

His older brother, Shaun, meanwhile, had lost his Cricket Australia contract despite courageously helping save a Test in the subcontinent.

So the Marsh clan set for the remote coastal town where they decamp to each year. It was a time for reflection and resolution about where they were heading.

"After the end of the season we all went away - Shaun, Mitch, the whole family - on a holiday up to Coral Bay," their father Geoff, the former Australian opener and national coach said at the WACA on Saturday.

"We go there every year. We all just sat around and had the best three weeks, chilled over everything and talked through where everyone was at. They came back and they started working really hard. That's what happens when you work hard."

Nursing a beer in the lower tier of the Lillee-Marsh stand the patriarch of Western Australia's most famous cricket tribe watched on with pride as his 26-year-old offspring reached three figures for the first time in his Test career, then passed 150 and beyond. On Sunday, he will begin only 19 runs short of a double century.

Marsh snr knows as well as anyone what the 26-year-old has been through to get to this point. He's seen at close hand the doubts and heard the doubters from afar. He also knows well about all the hours that have gone into dispelling them.

"It's been tough, no doubt. Test cricket is bloody hard," Marsh snr said.

"He's had to work really hard. When things don't go your way and you get injured and find yourself out of the team, you have to work hard to get back there. He's done that, and it's just really pleasing that he's come out and scored a hundred."

Marsh was there halfway across the world amid the tea plantations of Kandy in central Sri Lanka in 2011 when Shaun, eight years older than Mitchell, scored his maiden Test century for Australia, on debut no less. Four more have followed from the older brother - taking him past the old man's total of four - including the superb 126 not out at Adelaide Oval in the second Test of this series against England that justified his own controversial selection for the Ashes.

Mitchell, an all-rounder rather than an out-and-out batsman, had to wait a little longer, this being his 22nd Test, for his first hundred but when it came it was fittingly at home.

"Last week I was in Adelaide and it was the best moment of my life," Marsh snr said. "I come here today and this is the best day of my life. It's hard to explain...just really special."

Typically selfless as the Marshes tend to be, Mitchell points to Shaun's ton in Adelaide as being the one of greater significance.

"I think it was probably more special for Shaun because two months ago I can tell you he didn't think he was ever going to get to play for Australia again," Mitchell said.

"I remember sitting at his house when he got selected. We were just having a cold beer together and he was pretty emotional. For him to have done what he's done in the last couple of Test matches, it just shows you can't really give up."