Well, Im pretty sure Fergie got it for the prestige he brought to the English game, and the service he did to football, so more or less. Robson too has a good track record at clubs all over Europe. Souness....not so much
Becoming a Knight of the British Empire:
That's the knighthood that has honored people like Sir Paul McCartney, Dame Maggie Smith, and Rudy Giuliani. Other monarchies and even the French Republic award knighthoods. There are also fraternal organizations that refer to their members as knights, such as Knights of Columbus, a Catholic lay order, and the Knights Templar, a Masonic order. But British knightings tend to get the most attention.
The sovereign of the United Kingdom (currently Queen Elizabeth II) is traditionally referred to as the "fountain of honour," the source of titles such as knighthoods, awarded in recognition of service. Various honorific orders exist, but not all of them include knighthood. Recipients of the four highest orders, including the Order of the Garter, are personally chosen by the sovereign. The Cabinet Office of the U.K suggests the rest of the honorees for the sovereign's approval.
Anyone can nominate a British citizen for knighthood or other royal honors (although self-nomination is discouraged). Nominations from the public account for about a quarter of all recommendations. The Prime Minister and government departments usually submit the rest of the recommendations for the biannual Honors List.
Foreign nationals can also be knighted, but they are not allowed to use the title "Sir" or "Dame" before their names, although they can add "KBE" after their names. The U.K. Secretary of State for Foreign and Commonwealth Affairs usually nominates foreigners for knighthood and similar honors. Foreign knighthoods are conferred based on a person's contribution to relations between their country and Britain.