Oh well - here we go again...
BA used to have a large operation at Manchester - for a while they were pretty much the sole occupant of one the terminals. This included long haul flying to NYC.
Slowly, this operation was cut and offloaded because it lost money. One of the very last routes (the last route ?) was Manchester-NYC. Again, it just wasn't making money.
Have a search through some of the previous threads on here for all the times when Mancunians have bemoaned London Airways not giving Manchester a fair chance.