1946 stampless 'On Active Service' air mail envelope to Bombay, India, with a good strike of the extremely rare F. P. O. No. 127 29 APR negative seal canceller on the back. A Bombay 6 MAY 46 arrival datestamp is also on the back of the cover. Shortly after the Liberation of Hong Kong Indian Army units arrived in the Colony. Their Field Post Office No. 127 was at a camp in Kowloon. Very few examples of this canceller are known the earliest date recorded is 12 March 1946 and this is the latest date at 29 April. It is believed that less than five covers have been recorded with this negative canceller. A major Hong Kong rarity.