Clico perhaps need to research the web marketing gurus of Sheffield (and perhaps further afield to find a really good one) to find a firm that will build and host a clear, well presented site, spend time with Clico staff to train them how to update it regularly, and apply the tricks of the trade to get the site higher up the Google searches. Then think out some clear, concise, informative text that gets across the quality and unique features of Clifton planes. Add some good photographs (or even video clips) of the manufacturing process and the tools in use, and links to all the retailers stocking Clifton, and they'll have an electronic brochure that can be kept up to date. Quality is the key, though - there are lots of website designers; not all are that good.
Then perhaps they need to promote the website. A campaign of simple, clear adverts in the woodworking mags (nothing fancy, quarter page would do) to get people to look at the site and get the hits count up should do. No need to be every issue of every mag, either. Just often enough to be noticed.
Clico already demonstrate regularly at woodworking shows, which is positive face-to-face marketing well worth continuing.
Quality control issues - as far as I know - have long ago been addressed. I have three Clifton shoulder planes, two of them from their early production, And I've never had a problem with them. I haven't had to do any fettling beyond honing the irons, and I wouldn't part with them for a big gold clock. I also have an early Clifton replacement iron and stay-set capiron in my try plane, and no quality control issues there, either. Perhaps Clifton could add a note to their site to the effect that if you have a problem, no matter how old your Clifton, get in touch and they'll do their best to sort it - that, after all, is what they do now if comments on this forum are anything to go by.
Beyond that, I don't think Clifton ought to do anything much else. No gimmicks. No expensive stunts. In the end, reputation will count more than Schwarz's slightly bigotted 'not-made-in-America' attempts to trash the product. The planes will be around a lot longer than Schwarz will, after all - in all probability, Clico will be around a lot longer than Schwarz will.