Well, the history of the British knapsack is nicely outlined in Pierre Turner's excellent book Soldiers' Accoutrements of the British Army 1750-1900. Unfortunately, Frank Packer, who has done probably the most extensive research ever conducted on British knapsacks, has deleted all of his posts from the Living History Worldwide forums, where he had posted extremely detailed information about the subject.
So, I no longer know where you can find a detailed write up on the internet, but suffice it to say that there is absolutely no evidence that suggests the British wore knapsacks with wooden frames in the Napoleonic era. No images, no surviving examples, no mentions in documents or memoirs and the fact that John Trotter stopped trading in 1806, and the very detailed records of his company show that it had never supplied knapsacks, but rather camp equipment. There is, however, tons and tons of evidence that shows wooden frames were not used in the era. Every image that shows a British knapsack shows it as being the envelope type, or after 1812 a fully enclosed, but loose type.
If this guy can present evidence that suggests they existed, he'd be doing a great favour to the historically minded community by showing it. If he can't, then he's just someone that's decided something is one way and simply ignores any evidence to the contrary.
