I have just done it with this off e-bay https://www.ebay.co.uk/itm/144092505139

HHD6-G 1200W Input AC220V 5.5A Max Output DC 0-220V Motor Speed Controller 50Hz £30.44

It works a treat stripped it out and fitted into my own case with power in and power out to motor with the pot I get the veritable speed.

Phill