This is a Great Britain First Day Cover commemorating the Silver Jubilee in 1977 and the Army Air Day at Middle Wallop. The cover features an illustration of "The Sparrowhawks" Gazelle Helicopters, with a 10p Silver Jubilee stamp depicting Queen Elizabeth II. The stamp is cancelled with a special "ARMY AIR DAY BRITISH FORCES POSTAL SERVICE 6 AUGUST 77" circular postmark.

The cover is signed by LT. S. MURRAY-TWINN AAC, Team Leader of "The Sparrowhawks" Gazelle Helicopter Display Team. It notes the first public performance on 6 August 1977, featuring Gazelle AH Mk 1 aircraft XZ 316, XZ 317, XZ 319, XZ 320, with a flight time of 9 minutes. The reverse side features additional cancellations: a circular "ARMY AIR CORPS CENTRE MIDDLE WALLOP 6 AUG 77" and a "RAF AD/31 6 AUG 77" mark with jet aircraft imagery. This listing includes the single First Day Cover as pictured.

Verified Specifications:
Brand/Maker: Unbranded (Royal Mail / British Forces Postal Service)
Item Type: First Day Cover
Era/Style: Post-Decimal, Silver Jubilee
Material: Paper
Specifications: 10p Denomination, Signed by Lt. S. Murray-Twinn AAC
Theme: Aviation, Military, Royal Commemorative, Helicopters
Features: Special Event Postmark, Signed Cover
Included Components: 1 x First Day Cover
Country of Origin: Great Britain
Year of Issue: 1977