I would like to increase the flow/velocity of water coming from my shower. A plumber came round a while back for an unrelated shower issue and said they had decreased the flow rate and did this via the airing cupboard.
It can only be that they have turned down the stop tap, just open that back up by turning anticlockwise until it stops and then turn back 1/4 turn.
Why did they turn it down? Were they trying to increase the temperature? Your shower is a thermostatic electric shower, therefore as the cold water gets colder in the winter it will automatically turn the flow down to try to maintain the temperature, it's how electric showers work.
That shower is able to modulate the water flow and/or the amount of power in use, to match the temperature you set on the dial, so there should be no need to restrict the flow to it. What the 'unrelated issue'?
The water wasn't draining away properly so as a temporary measure they turned the tap down.
I'm guessing the stop tap is the copper pipe?
What does the Whale box control and what is the white tap below the stop tap?