I have /had one of these, complete with wooden grips and the Indian Army Liaison Officer at Warminster said that it was an Indian made L1A1 rifle bayonet with an extended length blade. They had longer blades to deal effectively with the thickly padded smock jackets Chinese Infantry based very close to the Northern Border in India.
That one shown even has the recessed catch - as per the EMER to make A1 and A2 bayonets into A3 and A4 variants
I didn't have a scabbard for mine and miraculously, one arrived for me a month or so later. With the compliments of the Indian Army.
I understand that the long scabbards are now available in the UK![]()