Bear Grylls products are not "marginal" as you put. The quality is as good as, and in many respects superior to other products on the market.
If that is true, they made a fairly poor business decision to market his stuff through Walmart, and have Walmart as a main sponsor of his current TV show. You may not have Walmart stores in the UK, but here in the US they do not have a reputation for selling quality stuff. Yes, you can occasionally find a decent product there, and if you do, it will sell for a price lower than probably anywhere else.
But there is a lot of complete junk in Walmarts. They are well known for striking deals with manufacturers, getting the manufacturers highly dependent on Walmart sales (they are a very big distributer), then turning around and telling those manufactures to make things cheaper and cheaper to hit a Walmart price-point. They've kind of got the manufacturers in their grasp, because those manufacturers have gotten so dependent on sales through Walmart that they don't want to, or can't, give up that revenue stream. You find some manufacturers that have two lines of seemingly identical merchandise, the regular stuff, and the Walmart stuff. The Walmart stuff is much worse quality.
Google "Walmart vs. Vlassic", or "Walmart vs. Snapper" if you want to read up on it. The two links below are samples of the kind of stuff you will find:
http://www.liveleak.com/view?i=bac_1342681195http://www.fastcompany.com/54763/man-who-said-no-wal-martSelling through Walmart, let alone having them be your primary sponser, may be the death knell for your company, or the cause behind your products going from a quality reputation to a trash reputation. Walmart is huge, and very popular for two main demographics: Lower income shoppers, and shoppers in search of a "bargain". That is not necessarily bad, but that is their targeted audience. You don't find folks looking for higher end stuff in a Walmart. No offense intended towards Walmart - I go there occasionally. For example, I like their "bargains" on the K-cups for my Keurig coffee maker. Those things are so horrendously overpriced at normal retail that I'm not overly concerned about Walmart putting those manufacturers in their place, price-wise.