I figure the British military invest more research into this than I do, so a pair of Bates Patrol boots from ebay for less than £30 delivered will do the job. You can get them from many surplus sellers in varying grades, but I found a pair from a seller who posted the actual photos of the boots he was selling. So I could see the state of the soles and uppers before buying.
They arrived today and are super light and very high on the leg. Not the sexiest bit of kit, but form over function for me. Add to that the sole pattern wont pick up bb's like my Berghaus' do, so I won't go clicking and crunching when trying to sneak about