Staff at the insurance market have been told that drinking is prohibited between the hours of 9am and 5pm, which the organisation said would bring it into line with other firms.
The ban is included in an updated version of the Employee Guide.
An internal memo circulated to staff said: "The London market historically had a reputation for daytime drinking but that has been changing and Lloyd’s has a duty to be a responsible employer, and provide a healthy working environment. The policy we’ve introduced aligns us with many firms in the market.
“Drinking alcohol affects individuals differently. A zero limit is therefore simpler, more consistent and in line with the modern, global and high performance culture that we want to embrace.”
Workers took to an internal messaging system to voice their concern.
One said: “Did I just wake up from my drunken drug induced slumber to find we are now living in Orwell’s 1984?
“Lloyd’s used to be a fun place to work. Now it is the PC capital of the world where you can’t even go out for a lunchtime pint anymore?” Another asked: “Will we be asked to go to bed earlier soon?"
A Lloyd’s spokesperson said: “Our employee guidance was recently updated and provided clarification on the Corporation’s position on drinking alcohol during the working day, which is prohibited.”