Sound advice from Ken as always.
Hello Adam.
I see you are a fellow Scotsman

there's a few of us on here.
I like Prespray Gold, but would most likely have rinsed with fibersafe gold or
maybe Fabric and Fiber Rinse if not to soiled.
"Fibresafe Gold
A safe and effective powdered extraction detergent for wool and stain resistant nylon carpets. Approved by the “Woolsafe” Organisation for use on Wool and Wool-rich carpets. Fibresafe Gold incorporates a self neutralising pH system which reduces the risk of colour bleed, texture change and re-soiling. Yellow powder with green apple fragrance.
Dilution 1 to 333 pH 8"
If your in Edinburgh and you fancy a chat, get in touch.
Rab