Enjoyable 60s romp with Macnee as Mr. Jerico, a thief/con-man with 'scruples' who is out to steal a big diamond from very rich man Russo (who you know is bad because he's played by Herbert Lom).
A fun film with a very Avengers feel to it, which should be obvious given the cast and crew. Allen is a little out of place, but Macnee and Lom are great, as is Laurie Johnson's score. I'll even admit against that Lulu's theme song is catchy. . . Apparently intended as a pilot for a Macnee series to follow The Avengers, but instead released theatrically (though in the US it only ended up as a TV movie of the week).
Thanks to Gerald Lovell for helping ID uncredited roles!