THE POWER PETROLEUM CO LTD commenced business in 1922 as dealers and distributors of petrol. The company was taken over in 1924 by the Medway Oil & Storage Co (MOSCO) with its headquarters being moved to the Isle of Grain in Kent. Around the same time another company came to prominence -

Russian Oil Products advert of around 1930. Through bad press ROP became to be known as "Rotten Old Petrol"
Russian Oil Products (ROP) and a connection was made in the press between ROP and MOSCO which seemed to suggest that the Russians had infiltrated the UK's oil market with the intention of controlling it. This of course was untrue but Power used the publicity to good effect and their business and brands started to grow - even though they did of course use Russian Oil which was cheaper. The company's advertised brands in 1931 were Power Premier and Power Petrol.
1935 saw Power enter into an agreement with the Ethyl Gasoline Corporation of America to add Tetraethyl to their petrol and a new brand was launched "Power Ethyl".

The Ethyl Gasoline Corporation sold their product to most British Oil Companies
Prior to this in 1934, Power Petroleum had been acquired by the National Benzole Co but had continued to trade under its own brands. In 1948 "Power Diesel" was introduced and by 1957 "Power Plus" was about to be launched when reorganisation within B.P. Ltd led to new branding and marketing strategies with the result that Power Plus became BP Super (Power Petroleum had come under the control of BP via the National Benzole Co which had just been acquired by Shell-Mex and B.P.).
The company's original logo was a diamond within a diamond with the words "Medway Oil and Storage Company" between the diamonds. This was later altered in the early 1930's to the single diamond shape with the "Power" brand within it. There was also another logo, a circle with entwined P's and the name "Power Petroleum". The early company vehicles were painted orange and chrome with the Power brand prominently painted on. Early globes in the shape of a diamond were made by the glass factories of Czechoslovakia but later globes were produced in the UK.
The first and last adverts shown below, dated 1931 and 1953, illustrate particularly well

The first NBC 'Power' diamond globe
the consistant Power diamond globe.
The other advert dated 1936 for Power Ethyl with the globe in the shape of a hand is a total departure but an interesting one that could only date to the mid 1930's when Power Ethyl was introduced. Slogans of the company were "At the sign of the diamond" and "Just try it". As the Power name was phased out in 1957 the National Benzole Company decided to use a re branded Power diamond petrol pump globe as their own - showing consumers that Power had not totally gone but had just moved on.