The final blow landed via email this week when Weir learned a complaint that a female coach had hurled his custom-built racing chair across a room in anger had been dismissed. Another athlete claimed to have witnessed Banks launch Weir's £3,000 carbon-fibre chair following a furious row during the Rio Paralympics last summer.
A full investigation involving British Athletics' human resources department ensued but the complaint was not upheld. When Weir found out, he posted on Twitter, vowing never again to compete in an international vest. 'I have been let down again,' he said. 'Today is the day I officially retire from GB. I will never put a shirt on again. Thanks British Athletics, what a joke.'
Weir cut a disconsolate figure after withdrawing from the marathon in Rio following a crash, bringing the curtain down on his final Paralympics. It meant he left Brazil empty-handed after failing to defend the four titles he claimed during a glittering week on the track and road at London 2012.
It was clear to the journalists gathered on Copacabana beach to listen to Weir deliver his Rio debrief that it was not only the sweltering September heat that was bothering him.
'I just felt I was stabbed in the back a lot,' he said, declining to elaborate. Only now is the story starting to emerge. Weir has promised to talk more on the issue when he holds a press conference next week to promote the London Marathon on April 23, which will be his final competitive race.
Whatever the full details, it is an undignified situation to befall an athlete who has been an inspiration for thousands.
Weir was awarded a CBE in recognition of his exploits at London 2012. A hometown boy who trains in Richmond Park, just a few miles away from London's Olympic Stadium, he lived up to his billing as the golden boy of British Paralympic sport.
An eyeballs-out sprint down the Mall to claim a fourth gold in the T54 marathon, not even letting up when victory was assured, rounded off a glorious, golden summer for Great Britain. In Paralympic sport terms he is the equivalent of Mo Farah, dominating his rivals year after year in his prime, but he does not feel he was always offered the same perks as his able-bodied counterparts.
Weir has been coached by Jenny Archer, a former fitness coach to Wimbledon FC's Crazy Gang, since his schooldays. The bad blood with Banks, the woman alleged to have thrown his chair, dates back to 2013 when Archer was overlooked for a top job at British Athletics.
Banks, the coach of one of his relay team-mates Richard Chiassaro, was made Britain's head wheelchair coach instead. Sportsmail understands the pair rowed in Rio and Weir felt deeply let down.
Weir and Archer met British Athletics chief executive Niels de Vos in November to discuss what happened in Rio. Weir later met British Paralympic head coach Paula Dunn, with whom he has a good relationship, but she could not persuade him to continue.
De Vos told Weir he wanted him to be part of London 2017, whether he competed or not.
A British Athletics spokeswoman said: 'While David first indicated in Rio he would not compete for GB again, British Athletics staff met with him last autumn to encourage him to be part of a memorable home World Championships in 2017.
'However, he further met with our Paralympic head coach early last week where he confirmed that he would not be returning to international competition.
'David has had a phenomenal career and his gold medal haul will remain one of the iconic memories of London 2012. All those at British Athletics who have worked with him wish him well in his retirement from international representation.'
Banks was on Tuesday night unavailable for comment.
