Different private purchase knives can also be found. These knives can not be classified as F-S knives, but they have some resemblance to them.

Many of them were used by the Auxiliary Units

The standard knives for the Auxiliary Units, which were planned to be British Guerrilla, were equipped with Wilkinson made F-S knife as the primary knife. This is documented in Robert Wilkinson Lathams book. Sometimes there was a second sidearm of their own choice.

The Auxiliary Units were specially trained highly secret Guerrilla units created with the aim of resisting the expected German invasion.
Courtesy of Clive Bassett

Normally equipped with F-S, but those who were not, were told to equip themselves with a knife of their own choice.

The original owner of this knife. S.E. Essex Auxiliary Units and commanded the following patrols: Canvey Island, Hockley, Rayleigh, Rochford and Thundersley.

He is wearing this knife.

The image was probably taken 1943-1944

Courtesy of Clive Bassett

It is a heavy knife with balance far away from the specifications of the F-S knife. It weights 430 gram (15 1/4 ounces).

It is a private purchase knife  most likely from Rodgers.

The Auxiliary Unit was the idea of Major-General Colin Gubbins. He visited local Home Guard commanders finding out from them who their best men were. The most important requirements for the volunteers was an expert knowledge of their own locality, a degree of physical fitness and an ability to keep what they were doing a secret.

Men in the Auxiliary Unit were formed into three special Home Guard battalions as a cover - 201 for Scotland, 202 for Northern England, and 203 for Southern England, but they were kept separate from the Home Guard. The Auxiliary Unit had HQ and training centre at Coleshill House, a Palladian mansion, about 10 miles from Swindon, with large parklands and woods very suitable for guerrilla training.

You can read more here:

 http://www.swindonweb.com/?m=2&s=625&ss=635&c=2524&t=Mabel+Stranks+on+the+BBC