I don't know if this was a factor, but having operated in and out of both JFK and LHR, the quality of ATC communications is very challenging at JFK.
I am sorry, but the JFK controllers all talk as if their hair is on fire, like a machine gun, and it can be very challenging to understand the instructions, whereas at LHR, controllers are calm and speak calmly.
I can't help feeling that if the JFK controllers were to speak slowly and calmly, aircraft would have a much less confusing and less stressful time at JFK. There may be valid reasons why they don't speak slowly, such as there not enough enough controllers, and if so this should be addressed.