Another fare I have been tracking is WTP from UK to NYC. The lowest I can find now is £527 return, LGW-JFK-LON, which is low, but what has changed is that the fare basis did have a 3 day rule at the weekend, the entire minimum stay clause has now been removed from the fare basis, and it just has the usual 12 month maximum stay. So you can go on Tuesday 17 and return Thursday 19 March. Unfortunately it can't be used on end-on construction (plus no stopovers) to get a cheaper Inverness departure.