> You're telling me that people go to lunch, drink a bottle of wine in an hour and go back to work?

Social lunch != working lunch

Though a pint or two or sharing a bottle of wine (not one each) at a working lunch is hardly unusual in Blighty.

> You'd be too drunk to drive.

One doesn't need to drive into London nor most commuter cities.

In the USA it's often called "day drinking" and it usually coincides with brunch (never heard the term "social lunch" here) on the weekend. As in "rosé all day", or "bottomless bloody mary's" with a brunch purchase, etc.

Well drinking on the weekends is normal everywhere so I don't know what is being conveyed here.