Large oil tanks were built at Popton and the terminal came into opertation in 1960, being officially opened in 1961.
Sketch from April 2011 Pembrokshire Life
I'm sure others will have more knowledge of this tham I do - but I remember the 'new' stiles in Middleton hedges when I stayed int he 1960s, and the fuss we had when selling the property to find documents relating to the pipeline!
According to http://www.pembrokeshirevirtualmuseum.co.uk/main_menu/trade_and_industry/oil/sites/bp.html the B.P. oil terminal at Angle Bay closed in 1985.