The ban, which will affect 200 employees at the bank's Old Broad Street offices in London comes just eight months after the Halifax relocated much of its treasury division, which manages the bank's liquidity and currency and interest- rate risks, from its eponymous home town.
The move to London has exposed the Halifax's treasury team to the City's booming entertainment industry, where traders are wined and dined by brokers in the hope of winning their business.
A spokeswoman for Halifax said: "We are following good market practice in line with other banks."
Asked how the ban would be enforced, she said it would be effective because Halifax employed "good professionals".
However, other seasoned City figures were surprised by this act of prohibition and said that they did not know of any other institutions that went so far as to try to impose an outright ban. Other Halifax employees are not thought to be affected.
One banker commented: "Alcohol is the oil which lubricates the City's wheels. I have never heard of anybody trying to ban it."
He recalled his employers sending him on a course to learn how to appear to be drinking heavily without consuming too much, rather than actually banning alcoholic consumption altogether.
The Halifax's decision may be the most draconian, but it is only the latest in a series of moves by banks to curb their staff's lunchtime refuelling habits.
Many bankers accustomed to regular and prolonged lunchtime consumption have been told recently to limit their entertaining to important clients and to keep their lunch bills down.
The arrival of big Wall Street banks in the Square Mile has brought a growth in the American work ethic, which frowns on mid-day drinking.