Gold, do you have a bypass?
My Mum had two separate ones - kept her going an extra 15 years!
And there's one around Avonmouth village which makes it a lot nicer place to live.
Oh ...
No I don't Dave, (tho' I have used one in the past) I use the flojet pumps and I get scrap batteries and use a smart charger overnight - as mentioned I have quarter turn taps on our belts.
I found my old analogue flow controller a hindrance - you'd have to wait a few seconds for pressure to build up if you turned it off for any length of time, it could be temperamental and I no longer use one.
All flow control (as in amount of water from the brush onto the window) is from the tap. So if I'm doing a few houses and one has say some old georgian windows or a leaky door I just set the tap lower and then go back to full pressure which is my default setting.