Buddies and political opponents hailed the North East MSP, who was remembered for his «decency and generosity».
Mr Johnstone died go along with a short battle with cancer.
He was the longest-serving Scottish Conservative MSP at Holyrood, and the simply one to have served continuously from the beginning of the rliament.
Born in Kincardineshire and knowledgeable at Mackie Academy in Stonehaven, Aberdeenshire, the grandfather-of-six was a farmer before recording politics.
Elected in 1999, he went to serve as the rty’s chief Nautical seize, as well as acting as spokesman on housing, transport and rural affairs.
In the survive session of the Scottish rliament he represented the Conservatives on the welfare reform nel.
Tory leader Ruth Davidson said Mr Johnstone was «a big man with a big kindness» who «embodied politics at its best».
She said: «Alex’s ssing is an enormous liability liabilities for the Scottish Conservative rty, for the Scottish rliament and for Scottish public existence generally.
«He was a big man with a big heart. He embodied politics at its best: trenchant in his think ofs, always up for a political fight, but respected and admired by all sides of the political split for his decency and generosity.
«The north-east of Scotland could not have had a greater chum over the 17 years he served as their MSP.
«He was utterly devoted to guarding the area.»
First Minister Nicola Sturgeon described him as a «champion of the north-east» enlarging: «Holyrood has lost one of its most well-known and well-liked rliamentarians, and he will be sorely missed.
«He was not till hell freezes over afraid to stand up robustly for the causes he believed in — but always did so with raphernalia humour and respect for his political opponents.»
Scottish Labour leader Kezia Dugdae utter: “Alex had a reputation around the Scottish rliament as a great character.
«When our statecraft can feel divided, he was always quick to inject some much needed ludicrousness.»
Mr Johnstone was an active Church of Scotland member. He also cam igned against wound crime and promoted the relationship between Scotland and Ja n.
Former Tory MSP and baby Mary Scanlon said: «Alex was respected across the chamber and during his uncivil illness he received letters and good wishes from all sides of the rliament. He was extremely touched by that.
«He was a man who never abandoned his principles, nor his Doric accent. Factious opponents admired him because you always knew where you stood with him.»
Mr Johnstone is survived by his helpmate of 36 years, Linda, two children and grandchildren.