Those looking for weekend appointments have to wait three weeks on average, while those who want to attend during working hours have to wait seven days.
According to L&G the situation is much the same across the country, with banks in Manchester, Swindon, Ipswich and Bristol all struggling to offer flexibility for weekend and evening appointments.
Jeremy Duncombe, director at Legal & General Mortgage Club, said: “For those who work full time, it is not always possible or practical to take time out of the office for mortgage appointments.
“As properties are in such high demand, and rates at record lows, many consumers are unwilling or unable to wait three weeks to see a bank adviser, especially if they are ultimately unable to help, forcing the borrower to start the process all over again with another lender.
“A great option for borrowers who find themselves in this position, is to visit a mortgage broker instead.
He added: “Broker not only have access to the whole market when it comes to assessing mortgage deals, but they often also have a greater flexibility of hours than banks, meaning that consumers will be able to cut down the waiting time when they’re ready to make an appointment.”