I think Decora Blind is in fact the company that richards.uk use to make them. You supply the measurements to Richards according to diagrams on its website, pay Richards and the blinds arrive from N Ireland. Dealing with Richards was easy and problem free
Mine were well packed, well made and relatively easy to fit but you might need a second pair of hands for the top channel.
It was money well spent. Dealing direct with Decora might be cheaper but I wasn't aware that Decora is set up to deal with the general public.