As an occasional non-rev/employee on Transatlantic Flights this recent summer, Meals in Economy are still complimentary/free of charge we only charge for Duty Free, Wines,Spirits, and Beer which is tacky because non-American carriers provide complimentary Spirits, Beer, and Wine.

Hope that answers your question OP. By the way since LHR leaves so late, the meal service is very abridged and will be served quickly somewhere over Boston