I think we invented this one. The bar served Black and Tans and they served Guinness shandies but not the combination. We'd be a large round tableful of sailors and we'd order eight or ten Guinnesses, maybe six or seven Bass Ales and a bottle of Bitter Lemon. As the stock of any ingredient dropped below the reorder point we'd resupply.

We also used Bitter Lemon as a mixer with Everclear in college at maybe one part BL to four or five parts Ec.