Toronto-Dominion Bank's (TDB) London office previously instructed more than 20 firms on UK, European, and Far Eastern legal issues, including the two magic circle firms.
But TDB has created a panel that consists of only Linklaters and Norton Rose, and it has a total annual budget of more than £4m to spend on fees.
Other firms that the bank's London office previously instructed include Eversheds, the London offices of US firms Weil Gotshal & Manges and White & Case, and Dublin-based McCann Fitzgerald which handled Irish issues.
It is understood that the new panel will be instructed on all legal issues coming out of the London office, unless a conflict of interest arises from the work.
Linklaters and Norton Rose will also advise the bank's North American branches on specific issues with Linklaters currently advising on Canadian asset finance deals.
A shortlist of Linklaters, Norton Rose, Clifford Chance, and A&O was created by the bank earlier this year and the four firms were invited to join a beauty parade.
Following this, TDB invited the firms in for one to one interviews on specific areas of expertise.
Sources say that by this stage the vetting procedure came down to a question of how the personalities in the different offices mixed rather than which firms had the most legal expertise - all four firms were seen as capable of handling the work.
Norton Rose was chosen because it has advised the bank for more than 20 years, while Linklaters was chosen because of the personalities involved.
Paul Nelson, head of Linklaters' financial markets group, and Norton Rose head of banking Stephen Parish, are the two main contacts for the bank within the firms. It will channel its work through them.
Parish and Linklaters head of banking John Tucker say they are very happy that TDB values its relationship with them above all others in the legal world.
Tucker adds: "We treat this appointment very seriously indeed, and the commitment that is required to fulfil the bank's expectations."