Sir Cadogan provavelmente não foi demitido por Sirius.
Embora a professora McGonagall realmente o questionasse se ele deixara Sirius entrar, ela só parecia chateada com Sir Cadogan quando pensou que ele deixara Sirius entrar sem a senha. Depois que ela descobriu que Sirius tinha as senhas, ela ficou com raiva do aluno que as escreveu, Neville Longbottom.
“Sir Cadogan, did you just let a man enter Gryffindor Tower?’
‘Certainly, good lady!’ cried Sir Cadogan.
There was a stunned silence, both inside and outside the common room.
‘You – you did?’ said Professor McGonagall. ‘But – but the password!’
‘He had ’em!’ said Sir Cadogan proudly. ‘Had the whole week’s, my lady! Read ’em off a little piece of paper!’
Professor McGonagall pulled herself back through the portrait hole to face the stunned crowd. She was white as chalk.
‘Which person,’ she said, her voice shaking, ‘which abysmally foolish person wrote down this week’s passwords and left them lying around?’
There was utter silence, broken by the smallest of terrified squeaks. Neville Longbottom, trembling from head to fluffy-slippered toes, raised his hand slowly into the air.”
- Harry Potter and the Prisoner of Azkaban, Chapter 13 (Gryffindor versus Ravenclaw)
Depois disso, fica claro que Neville é a pessoa que a Professora McGonagall falha por Sirius ser capaz de invadir. Neville é punido severamente e não tem permissão para saber as senhas.
“Neville was in total disgrace. Professor McGonagall was so furious with him she had banned him from all future Hogsmeade visits, given him a detention and forbidden anyone to give him the password into the Tower. Poor Neville was forced to wait outside the common room every night for somebody to let him in, while the security trolls leered unpleasantly at him.”
- Harry Potter and the Prisoner of Azkaban, Chapter 14 (Snape’s Grudge)
Não parece que McGonagall considerou Sirius capaz de quebrar a culpa de Sir Cadogan - ele deixou Sirius entrar porque tinha as senhas. Em vez disso, ela colocou a culpa diretamente em Neville por manter uma lista das senhas.
Seu posto provavelmente era sempre temporário.
Embora a Professora McGonagall tenha ficado surpresa ao saber que Sir Cadogan deixou Sirius Black entrar na Torre da Grifinória, a razão pela qual ele foi 'demitido' pode ser simplesmente porque a Senhora Gorda terminou de ser restaurada e, portanto, capaz de retomar o emprego. Sir Cadogan sendo removido como guarda da Torre da Grifinória coincidia com a Senhora Gorda sendo totalmente restaurada e retornando ao seu trabalho.
“Sir Cadogan had been sacked. His portrait had been taken back to its lonely landing on the seventh floor, and the Fat Lady was back. She had been expertly restored, but was still extremely nervous, and had only agreed to return to her job on condition that she was given extra protection.”
- Harry Potter and the Prisoner of Azkaban, Chapter 14 (Snape’s Grudge)
Sir Cadogan nunca foi a escolha ideal para a guarda da Torre da Grifinória. Quando a Mulher Gorda foi atacada, a única razão pela qual ele conseguiu o emprego foi porque ele era o único que estava disposto a aceitá-lo.
“The Fat Lady’s ripped canvas had been taken off the wall and replaced with the portrait of Sir Cadogan and his fat grey pony. Nobody was very happy about this. Sir Cadogan spent half his time challenging people to duels, and the rest thinking up ridiculously complicated passwords, which he changed at least twice a day.
‘He’s barking mad,’ said Seamus Finnigan angrily to Percy. ‘Can’t we get anyone else?’
‘None of the other pictures wanted the job,’ said Percy. ‘Frightened of what happened to the Fat Lady. Sir Cadogan was the only one brave enough to volunteer.”
- Harry Potter and the Prisoner of Azkaban, Chapter 9 (Grim Defeat)
Portanto, parece altamente provável que ele sempre fosse retirado do posto assim que a Mulher Gorda pudesse e estivesse disposta a voltar ao seu lugar, guardando a Torre da Grifinória.