Three months after his departure from St James’ Park, Kevin Keegan has begun legal proceedings against Newcastle United, with his solicitor officially lodging a multimillion-pound claim for constructive dismissal against the club. The former England manager left Tyneside in controversial circumstances in September amid allegations of interference at boardroom level in first-team affairs.

Newcastle’s position is that Keegan submitted his resignation, although he will argue that he was effectively forced from his position. Having been given public guarantees by Mike Ashley, the club’s owner, and Dennis Wise, the executive director (football), that he would have the final say on transfers, the allegation is that players were signed without the manager’s approval.

The matter will be heard by a three-man Premier League tribunal at which evidence will be heard from Keegan, who is claiming that he is owed £8 million over the almost three years that remained on his contract, and Newcastle officials. The tribunal is empowered to rule on the issue, although disagreements would be dispatched to the High Court for final arbitration.

It is thought unlikely that the process will stretch that far, with a settlement — probably before Christmas — a more realistic outcome. Keegan, however, has been determined to fight his corner, both on a point of principle and financially, having seen his second managerial stint at Newcastle end in such a disappointing manner.

Having electrified the club, the city and supporters after his appointment in January this year, differences emerged between Keegan, Wise and Ashley over the running of the club and the separation of their duties. His exit dismayed the fans, prompting passionate protests, the formation of the Newcastle United Supporters Club and causing Ashley to announce that he would sell Newcastle.

While Joe Kinnear, Keegan’s replacement — initially on an interim basis and now on a season-long contract — has, up to a point, stabilised results, Newcastle are entrenched in a relegation battle in a season that, at one stage, had promised so much.

Keegan remains popular with players and supporters, although there is little chance of him returning to the club in the event of any takeover. It is alleged that Keegan had been told that he would be permitted to reinvest the £12 million proceeds of James Milner’s sale to Aston Villa in August, but that the signings of Xisco, the 22-year-old forward from Deportivo La Coruña, and Ignacio González, the 26-year-old midfield player from Valencia, on transfer deadline day were made above his head.

In subsequent negotiations with Ashley, Keegan refused to return to his role unless the influence of Wise and other directors was curtailed.