Unlike many publicly quoted companies, Bank of Ireland has no deputy chief executive to take over on an interim basis from Mr Soden. Executive responsibility for the time being rests instead with an executive committee under the guidance of chairman Laurence Crowley.
The bank is understood to favour a quick succession after the weekend's surprise events. This means the shortlist of candidates to replace Mr Soden is likely to be made up exclusively of current executives.
This is in stark contrast to the lengthy process carried out by a board sub-committee in 2001, when a firm of executive headhunters was hired to trawl banks around the world to replace then chief executive Maurice Keane.
Senior banking sources said yesterday that the bank would move quickly to draw a line under the series of events that resulted in Mr Soden's departure.
The front-runner to take the top job in Baggot Street is Brian Goggin, the current head of the bank's impressive asset management arm. Mr Goggin is a career banker who has made his name in several high-profile jobs across the bank's retail, corporate and life assurance businesses. Many within the bank felt Mr Goggin missed out at the time of Mr Soden's appointment.
Also in the race is Des Crowley, head of the bank's core retail banking division.
Mr Crowley blazed a trail through the bank since joining from management consultants Andersen (now Accenture) and has a strong track record from spells in charge of the bank's asset finance and credit card businesses, as well as a stint in charge of retail strategy.
Mr Crowley's remit was recently extended to include responsibility for the bank's retail businesses, to add to his existing job as head of the branch network.
Other names that have been mentioned include head of wholesale banking Denis Donovan and operational risk chief Ronan Murphy, who previously headed up the bank's successful international lending division.
But both men are relative newcomers to the top executive ranks and Mr Soden's departure may have come too soon for them. Finance director John O'Donovan, ironically a former executive at Aer Lingus, is also a possibility.
Meanwhile, sources close to Aer Lingus said over the weekend that the vacant chairman's position would not be filled with the same urgency. The company hopes to install a new chairman before the next board meeting, which is scheduled for July 26.