Following David Green’s letter (Letters, Newsletter 76), I agree that Schwalbe Marathon HS 308 are good, but not against thorns. I switched to Schwalbe Marathon Plus on my utility bike, which does about 2500 miles a year. They have a thick pad of very springy rubber under the tread, but, surprisingly, still roll at least as well as the standard Marathons. They are more expensive and more difficult to fit, because the thicker rubber tends to spring out of the rims; I resolved that with a set of 4 “zip ties” to strap them on as I worked round the rim. I think they are worth the extra cost and more time-consuming fitting for peace of mind when cycling in poor conditions.
Mine came from Spa Cycles by mail order.