Alisher Usmanov’s talk of acquiring a “blocking stake” is in reality a form of hard-ball negotiation - with a 21 per cent share of Arsenal, he cannot be ignored by the North London club’s under-pressure board.

Every share he acquires increases his ability to make trouble, and he gains some extra rights if he passes 25 per cent, but if the Arsenal board stays united it may remain in the driving seat.

At 25 per cent, the Russian and David Dein, who is the chairman of Red and White Holding, Usmanov’s company that owns the shares, can block any “special resolution” that the Arsenal directors might try to pass. Usmanov can go as far as 29.9 per cent, but beyond that he would have to make an offer to all investors, who are not bound to accept.

Yet, while crossing 25 per cent sounds impressive, advisers to the club’s board believe that it carries few meaningful rights. A quarter shareholding means that Usmanov can prevent Arsenal’s directors from fundraising by issuing new shares and from actions such as changing the name or winding up the business.

He can also make it difficult to force through certain types of takeover that are advantageous for tax reasons, but if somebody can reach an agreement to buy 50 per cent plus one share, it is they who are in control.

Usmanov and Dein can also try to force change by calling an extraordinary general meeting and try to get their people on the board. But with the existing board controlling about 45 per cent, it is hard to see it being beaten, even if the invaders can win the backing of Stan Kroenke, the American, who has a 12.2 per cent share.

And there is no obligation, despite the size of the Russian’s investment, to give him or Dein a seat on the club’s board.