1927. RAF Display Flight. Flown Risalpur-Delhi and then to Calcutta. Cover has a special " By Aeroplane" label. Delhi RAF delivery stamp & Calcutta delivery stamp.
This cover could be an unique cover - a non-philatelic first flight cover. Cover mailed from Poona addressed to England would have gone to Bombay then to Karachi to catch the Imperial Airway flight to London. It went to Karachi from Bombay on the return Madras-Karachi first flight. The cachet was applied at Bombay.