The Vice President of the Court of Appeal, Lord Justice Rose, said the sentence was "not out of line" with other fraud jail terms and he could not intervene over disputes between prisoners in jail as there were other remedies available.
The appeal had been hailed as a test case over whether jail terms should be reduced for inmates assaulted in prison. The Court of Appeal last month granted him leave to appeal after hearing the peer was knifed and violently assaulted while in jail.
Lord Brocket, 45, a sporting friend of the Prince of Wales, has been in jail for 20 months and now faces a release date in August next year at the earliest.
Steven Barker, his solicitor, said after the hearing on his way to the cells to visit the peer: "We are very disappointed. Lord Brocket had his hopes up high."
Asked if Lord Brocket would apply for compassionate early release he said: "It is too early to say what will happen."
Lord Brocket was jailed at Luton Crown Court in February last year after admitting that he arranged to have four classic Italian sports cars "stolen" in a bogus raid on the family home, Brocket Hall, his 5,000 acre estate in Hertfordshire.Reuse content