I just got a second hand HELVETIA stainless steel camping stove, does anyone know what gas bottle fits the helvetia. Has anyone ever heard of Helvetia? They're made in UK, but the web gives nothing about them. I have pasted some pictures if it below here, including one which shows the fitting for the gas bottle. I mainly want to know what gas bottle will fit this stove.

Thanks, Tony

Here are some pictures of the stove