Hairy Legs and FALs
Well, technically inch-pattern L1A1s with early knife-style bayonets rather than true FN FALs, but still…

Note the “JAG3” rack markings on the stock of the rifle on the right, and the Soviet Red Naval banner shown on the passing destroyer. Crown copyright. IWM (A 35389) IWM. Original Source: http://www.iwm.org.uk/collections/item/object/205165189
Official caption:
HMS Jaguar (F37) at Ethiopian Navy Days, February 1972, Masawwa Ethiopia. The frigate HMS Jaguar represented the Royal Navy at the annual event, in which the navies from Ethiopia, Britain, American, Russia, France, and Sudan took part. As the ships gathered at Massawa this shot taken from HMS JAGUAR shows her White Ensign and the Soviet Red Star of the Kashin-class (Project 61) destroyer Stroggi [sic].
Jaguar was a 2,500-ton Leopard-class (Type 41) frigate commissioned in 1959. A globetrotter, she completed a world cruise in 1969 and repeatedly went toe-to-toe with the Icelandic Coast Guard in the “Cod Wars” during which she was fitted with add-on lumber armor to absorb the impact from ramming ICG gunboats. Jaguar decommissioned in 1978 and transferred to Bangladesh as BNS Ali Haider (F17), serving until 2014.
As for the shorts, and FALs, they just historically go together.