David Chaytor has failed to persuade the High Court to reduce the 18-month jail sentence he received for fiddling his expenses.
The 61-year-old former Labour MP argued that 12 months would be more “appropriate”.
Announcing the decision, Lord Judge, sitting with Mr Justice Henriques and Mr Justice Foskett, said: “This was a grave breach of trust and there was a further aggravating feature of this case.
“It is difficult to exaggerate the levels of public concern at the revelation of significant abuse of the expenses system by some Members of Parliament.
“Some elected representatives, vested with the responsibility for making the laws which govern us all, betrayed the public trust.”
He added: “There was incredulous consequent public shock.
“The result was serious damage to the reputation of Parliament, with correspondingly reduced confidence in our priceless democratic system and the processes by which it is implemented and we are governed.
“This element of damage caused by the appellant and others cannot be valued in monetary terms, but it is nonetheless real, and the impact of what has been done will not dissipate rapidly.”
Chaytor, a former Calderdale councillor, still owns a home at Lumbutts, Todmorden.
He was jailed on January 7 for forging tenancy documents and invoices to falsely claim more than £22,000 of taxpayers’ money for rent and IT work from the Commons authorities.