Dobbo - if a flight leaves Manchester about 10 am local time, it arrives in New York around 1 pm local time, leaving plenty of opportunity for passengers going elsewhere in North America to catch onward connecting flights.
Change that 10 am departure from Manchester to a 7 pm departure, allow for a couple of hours for immigration and changing plane and the number of onward connecting short-haul flights leaving New York around 11 pm is pretty small. Spending a night at JFK is not a particularly popular option amongst those who are time-poor, cash-rich and travelling business class - i.e. the most profitable customers.
London can manage an evening departure to New York because the number of people travelling just between these two cities is so large. Manchester doesn't have this luxury.
Now factor in that an aircraft leaving Manchester around 7 pm probably has to arrive in Manchester about 5 pm to have a decent chance of offloading passengers, clean the aircraft, load catering, new passengers, luggage, and allow a margin for small delays. That means the aircraft has to have left New York about 6 am local time. Domestic flights within the USA would have to arrive in New York about 4 am to give a fair chance of making the connection - i.e. really not popular with most connecting passengers, never mind any night noise rules the airport might have to obey.
Barring any special holiday events, flights from Manchester to New York run on a commercial basis pretty much have to leave no later than UK lunchtime to be commercially viable.
Last edited by davidjohnson6; 16th Feb 2016 at 23:15.