CEJM,
I've just checked the current chart in the NATS IAIP ENR Section and Class F isn't mentioned. I think it changed late last year and in fact I've just found a copy of the same chart which I used in a presentation last November which also shows its reclassification to Class E.
ENR 6-1-4-1 is the reference to the current chart....AIRAC 10/2015.