Well, you asked for it: Here goes “Classic Traction Roundup” in a nutshell:
08: Scattered around yards and depots all over the country. They see a lot less use than they did in the 70s and 80s, but in many cases they are still dumped in the yards they once served. Plenty still in use for various applications though.
20: Direct Rail Services refurbed a fleet of fifteen “20/3s” between 1995 and 1998, and these are all still on the mainline, though now employed by a range of operators. Harry Needle also has about four on the mainline for charters and freight work, there’s a few in industry (Two at Scunthorpe Steelworks, one at Lafarge Hope Cement, etc) and plenty in preservation.
25: A number are preserved. One (25278) on the North Yorkshire Moors Railway has dispensation to work over Network Rail metals between Battersby Junction and Whitby.
31: Network Rail have around eight operational on the main line for use on test trains around the country. Many others are preserved.
33: West Coast Railway Company have 3 or 4 that could potentially be used on the main line, but realistically there’s only two that venture onto Network Rail metals. This number was slightly higher about five years ago when Direct Rail Services had four and Fragonset (Spot hire company and tour operator), now defunct, had about five.
37: Popular with railtour operators, West Coast Railway Company have a good number and Direct Rail Services operate several commercially. Theirs is an absolute shedload of 37s in preservation, in varying states of wellbeing. Seriously, the number of 37s that have gone into preservation is staggering.
40: Several in preservation (At least four). 40145 is mainline registered, currently running around in unauthentic large-logo blue but due a repaint soon.
44: Don’t take this as gospel, but I believe there are two preserved: (I think) 44004 and 44008.
45: There’s a few of these in preservation, and 45112 is currently (or was up to a little while ago) the only main line registered peak. 45118 can also be seen from the MML at what used to be Derby RTC as it is awaiting restoration.
46: One or two in preservation: 46035/D172 “Ixion” has been on the main line in the past.
47: Given how ubiquitous these locos once were, there’s a lot of them made it into preservation at sites all around the country as you can imagine. Class 47 preservation really kicked off once the 47/4s began to be withdrawn en masse in the late eighties. There’s also still a few knocking about on the main line carrying out freight or charter work with smaller operators: Riviera Trains, West Coast Railway Company and Direct Rail Services are the main progenitors I would say. Riviera Trains have a sizeable chunk of the remaining 47/8 fleet and several locos are always visible south of Crewe station, where Riviera are based.
50: An awful lot of the original fleet of fifty locos was preserved following withdrawal in 1992. Not all of these are likely to run again and a few are rather dilapidated. 50031, 50044 and 50049 were main line registered a short time ago, a couple of others have main line operation beckoning, and there’s a few operating on preserved lines.
55: There’s a few in preservation: 55022 (D9000), 55002, 55009 (D9009), 55015, 55016 and 55019. The Deltic Preservation Society is based at Barrow Hill, so there’s normally a couple kicking about there, and there’s normally a couple main line registered for charter work at any one time: I think the current mainline registered locos are D9000 and 55016, and both 55009 and 55019 have been on the mainline in the recent past. 55016 was the subject of a bizarre overhaul by Porterbrook over ten years ago that saw it fitted with UIC headlight clusters and painted purple and it has only recently been returned to something nearing original condition and BR Green livery.
56: DB Schenker are nearing the end of a major purge of all their 56s that have been in store since the final class members were withdrawn from regular service in 2004. That’ll leave just the locos that are in preservation (About five or six? I can think of 56003, 56006, 56040 and 56098 off the top of my head) on preserved railways, and a total of five that are/have recently been mainline registered for commercial use: Fastline Freight operated three locos on a regular container flow up until a couple of years ago before the company went bust, and as far as I’m aware they’ve since passed into obscurity since recently being offered for sale. Two further locos are operated by Hanson Traction and are used on a Washwood Heath-Boston Docks steel train.
HST: HSTs are everywhere! Except those that have been disposed of following accidents, they’re all still extant and in use: East Coast now have a couple more sets (11 trains in total?) than they had immediately after the East Coast main line was electrified in the late eighties. Their use on the Midland Mainline has been reduced to ten sets in service with EMT, following replacement by Midland Mainline on the vast majority of services by Class 222 “Meridian” DMUs. They are now principally confined to working London-Nottingham services. First Great Western are by far the largest users of HSTs, on all Paddington-Bristol, Cardiff, Swansea, Plymouth and Penzance trains, just as things were in the eighties. Crosscountry have five HSTs working four diagrams each day between Edinburgh and Plymouth, which are the only ones you’ll see in Birmingham.