When one stops to consider -- this is indeed alternative-history territory, with quite a potential number of different ways in which things might have gone; and with increasing numbers of possible alternative consequences, of the different paths taken.
Maybe not much more than what is in the NRM? Plus the narrow gauge of course.
Yes, the narrow gauge would indeed be a different kettle of fish: likely enough, narrow-gauge preservation would have gone a lot like it has in "Our Time-Line"[OTL].
If steam had been phased out more slowly, BR would probably have continued to scrap all the withdrawn locos rather than sell any to scrap merchants. It was only when large numbers of steam locos were being withdrawn that scrapping exceeded BR's own capacity, and sales to scrap merchants commenced.
BR did sell a few locos direct to preservationists and that would probably have continued. However, there would not have been a "Barry-style" source of steam locos for "latecomers" to the preservation movement.
Lines obtained by the heritage movement would probably be similar to the Bluebell Line or Worth Valley Railway - mostly shortish branch lines (or sections thereof), often in rural areas or serving villages / very small towns. Lines like Minehead, or the Great Central would still be part of the national network, although some of the lesser-used stations might have closed.
It would seem clear, indeed, that in a situation of far more of the network lasting a lot longer than in OTL: lines taken over by preservation societies would be relatively minor and marginal ones. Pace
Cowley, possibly in fair numbers in any halfway-realistic scenario, some lines closed in the 1960s in OTL, would perish in the 60s or later, even on a scene of an overall better history for lesser lines than actually came to pass. Just, many of the lines which got preserved, would be different ones from those of OTL.
A thing which I can get a bit bigoted about: I, personally, regret that so much of the preservation movements potential effort is dispersed in what I see as silly, piddling little three-men-and-a-dog outfits; rather than people concentrating on fewer, but bigger and more worthwhile, more-established lines. Id be willing to bet that this phenomenon would be the same even if with different locations -- in our alternative scenarios as above. With my head, I can see how and why this thing is: people are not natural communists, and many of them prefer being a daft, piffling little wheel in their own right; to being just a cog in someone elses large-scale, magnificent wheel. Also, folk tend to like to have a project which is on their doorstep and convenient to get to.
(A rather flippant aside: I had forgotten the date of BRs closing of the Worth Valley line: looking it up, I found that the branch passenger service was withdrawn as from Jan. 1st 1962. In my genie scenario in the other thread, I hypothesised most of the network as at the very beginning of 1962, long remaining in service: whereby the Worth Valley branch might just make the cut, and be in action as part of the national rail system for decades thereafter, delivering one hopes railbus-loads of Brontë devotees to Haworth.)
Bevan Prices thoughts on different circumstances of availability of steam locos to preserve, given a situation of steams being phased out more slowly and sensibly: prompt musing on how things might have been, overall; given a higher degree of co-operation / friendship / assistance from the national rail undertaking, toward the preservation movement.
The picture I get is that in OTL, in the 1960s BRs attitude was more than a little hostile to anything which smacked of nostalgic / reactionary sentimentalism: they tended to make things difficult for preservationists, rather than go at all out of their way to help them. An instance that comes to mind, is the trouble which many preserved lines have long had, as regards making direct connection with main-line services. Some e.g., once again the Worth Valley -- have been lucky in this respect, thanks to the chances of how their infrastructure had developed. Others have been less fortunate; as, say, the West Somerset and its being unable to run regularly into Taunton. (In circumstances such as WSR / Taunton as just referred to, one sees the national networks point of view: very difficult to run frequent, slow branch-line trains between Norton Fitzwarren and Taunton station, without great disruption.)
One wonders what might have come about, in a situation of a national network which was both bigger, with many relatively lightly-trafficked rural lines; and more disposed toward help and co-operation vis-a-vis the preservation movement; than was the case in OTL. Greater possibilities for direct passenger connection national network / preserved line, at lightly-used country junctions?
Perhaps even, its being possible to work things out for preserved steam-hauled trains to share regular passenger workings over some rural lines, with the national networks modern diesel railmotors? That is, maybe, crazily optimistic: from my limited knowledge of preservation on the European continent, such stuff seems to occur little there, if at all (Wolsztyn in Poland maybe an instance of its happening) but our famously eccentric nation often does things differently from that lot over there...
Edwin M said it would be interesting to compare ourselves with other countries that did do things more slowly than ours and I've often thought that it would, but I bet when you compare ourselves as a country we're a real one off when it comes to railway sentimentality (with a nod there to Mr Calthorpe).
I'm not so sure -- as I've mentioned on the forum before, that's a thing which the Germans, too, are very big on. And railway-enthusiast numbers in the USA, are legion: many of them steam fans, keeping preserved steam action going -- albeit "real" steam came to an end in the US, overall quite some years earlier than in Britain -- an American would in the main have to be at least in their late sixties, to have meaningful memories from childhood, of "the real thing".
Re detailed comparisons -- one feels that yet another thread is perhaps indicated::-x (in "Railway History & Nostalgia"; or in the "International" section?).
