The greatest irony is that Lydgate never really knows the full extent of the social cost incurred by following one's ambitions at the expense of another person. He didn't know that the marriage prospects of either Farebrother or his sister depended on his vote. Neither does he know that his act of redemption made any bigger difference in Farebrother's life beyond alleviating the pressure to gamble. Eliot clearly demonstrates that ordinary actions made by ordinary people can have a truly significant impact.
Farebrother considers himself a mediocre clergyman. He regards his choice of profession as a mistake. Certainly, he does not pretend to be a saint. He is merely an ordinary man in a small, provincial community who puts aside his own personal desires when a member of his flock comes to him for help. Farebrother knows that the success of Fred's courtship of Mary entails far more than a broken heart that can heal over time. Fred is on the brink of choosing the wrong vocation, and only Mary can save him from this. Farebrother knows the consequences of becoming a clergyman when one isn't suited to the occupation. He gives up his own interest in Mary, the chance to overcome his own unhappy entrapment in the wrong vocation, when he acts as Fred's representative to Mary. Because he is a mediocre clergyman, Farebrother overcomes his flaws and becomes an exemplary clergyman for a short while. It is a quiet moment of dignity that will not be recorded in any historical record, but it is a noble moment that greatly affects other human lives for the better.
Bulstrode's world is about to come crashing down around him. The contradiction between his public self and his private sins is about to come to light. It is money that leaves the trail that Raffles follows. A letter written to Joshua Rigg Featherstone regarding his purchase of Stone Court is the clue that leads his tormentor to him. Bulstrode makes the mistake of using the same tainted money to try to cover the trail by bribing Raffles to leave Middlemarch.