hopefully one day New York may become a regular flight..
There used to be a market for economy trips to NYC on a non daily basis, however the huge growth of legacy long haul connectivity killed that stone dead. Why pay a premium to fly on an old American Trans Air TriStar once a week when BA/KLM offer multiple daily frequencies on a more comfortable product.
A weekly shopping flight is all economy, a daily offering would demand a better balance of business and leisure. In terms of the UK, EDI has huge inbound market presence, GLA less so but still high and MAN has a lot of business it terms of the leading regional airport. BHX just has a single UA flight to Newark and LGW can't hang onto a single JFK as LHR being so close just kills it, less so but similar for BHX.