Pubs using a flat roof were one of the first chains, or at least pubs of a similar design, built by Whitbread in many parts of the country.
Many were built on council housing estates and all used a bird as their name - Mallard, Moorhen, Raven, Eagle, Falcon, etc.
The flat roof was used over the bar area because they wanted more room downstairs than up.
A lot are now shut/demolished/renamed, but if you look around a council or 60/70s estate in your area, you may still see one, or the remnants of one.
This pic is of the Mallard, in Seaham, County Durham.
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