1966 UNDERPAID MAIL USA TO WEMBLEY MIDDLESEX. Window envelope (240 x 105) USA to Wembley with US .05c meter mark DOWNERS GROVE/ILL dated MAR 4 66, postage underpaid with UK "6½D/MORE TO PAY INSUFFICIENTLY PREPAID" instructional with ½d orange and 6d postage dues cancelled WEMBLEY.MIDDLESEX 15 MR 66. Filing fold clear of stamps. (Ref 111324).
