Great Britain 1971 Fylde Coast Envelope Phosphor Varieties Postal History

Great Britain 1971 (May) Fylde Coast Used Envelope Bearing ½p Turquoise-blue HORIZ PAIR Both with Varieties: (i) One Left Broad (8mm) Phosphor Band & (ii) 2p Myrtle-green Single with 7-8mm Left Phosphor Band with Very Narrow Band Right. Stamps Probably from X841l Booklet Pane. X841/849