Note the square body edges and single colour (grey?) covering of the new amplifier's cabinet. Controls are not yet top-mounted.
By August 1958, tremolo is available as an option on the Westminster, and a more powerful "15-20" watt version is available.
Similar information provided in August 1958, but the output of the more powerful Westminster has been upped to 20 watts.
A clearer version of the May 1959 advert giving prices for the Westminster 10w and 17w Tremolo models, the Westminster 10w and 17w "standard" (non-tremolo model), and a 6 watt "standard" (non-tremolo model) which was presumably soon to be called the "Clubman".
An advert for Watkin's first solid guitar, the Watkins Rapier. However, the amplifiers made at that date by the company are listed out and show that the 17watt amplifier has now been given the name "Dominator" and the 6watt is called the Clubman. It also seems to confirm that the later 14w Westminster has not yet appeared.
The Dominator is the model featured in this advert. However, the 14 watt Westminster has also now appeared, indicating that this new model must have been introduced to the range sometime during the period July 1960 to April 1961.