An aggressive approach to acquisitions and a tough management style helped them to become Britain’s most successful industrialists, and the pair formed a close bond.
Ratcliffe was the strategist, and MacLean the hands-on operator. Witness the battle with the unions at the troubled Grangemouth refinery. MacLean was in charge, and Ratcliffe flew up to Scotland to check on progress.
A nail-biting set of tactical manoeuvres followed, with MacLean threatening to shut down the huge refinery unless working conditions changed and the firm received a government guarantee on a loan.
Eventually, MacLean won out and the site remains open.
But that tight relationship is now in tatters. Ratcliffe is set to sue MacLean for millions of pounds of his enormous leaving settlement, arguing that MacLean poached a top member of his finance team for the new job as chief executive of Synthomer, breaking an agreement when he left Ineos.
As well as a legal battle potentially in the works, the pair could end up as rivals. Ineos has carried on expanding with a series of bold investments since MacLean’s departure in November.
But MacLean also has an ambitious plan to expand his new firm. In November, Ineos revealed plans for a $1bn investment in shale gas.
And MacLean wants to double or even triple the size of the FTSE 250 chemicals firm, using his trademark aggressive takeover strategy.
Targets are expected to include global groups selling off non-core units, which Synthomer could buy up in relatively quiet deals – a successful strategy which helped Ineos grow.
Analysts at Numis met Synthomer executives last month, and speak in glowing terms about MacLean’s abilities and potential.
“Calum MacLean has the extensive industry contacts and he also has his track record of close to 17 years at Ineos on his side,” said Numis’ Charles Pick after the meeting.
Antagonising a man as powerful and dogged as Ratcliffe, however, may not have been MacLean’s best move and could prove a costly distraction.