The fabric glue I have always used is called Bondaweb, which comes as a "web" with a paper backing, and you cut a piece more or less the right size, with its paper backing, and iron it on to the back of the badge, then cut round the edges, peel off the paper backing, and iron onto the garment. Full instructions on the pack! I'm sure Creations in Turnham Green Terrace will sell it.
Barbara Robinson ● 1868d