I was at Muharraq in 1969-70. At that time, there were occasional visits by a single PR9 from Malta, for maybe a week at a time. They also visited Masirah once in a while.
Not sure about Marsovin in this context - I never saw any brought to the Gulf. But in the Transit Mess at Luqa, diluted 1:3 with Coke, known as "Screech and coke", a frequent tipple. Screech was how you reacted if you drank the stuff undiluted.