I've been thinking further on the subject of the 1938: Very British Civil War setting. There's something compelling about the idea of civil war. There's the "brother against brother" element of tragedy, plus the irregular and sometimes colourful forces that always seem to crop up in civil conflicts. VBCW seems to be the most prominent example at the moment.
But it's not the only hypothetical English Civil War 2/3 (depending on how you count it) that's floating around out there. Back in the 1990s James Clay wrote a series of articles about a hypothetical UK civil war as an alternative setting for ultra-modern wargaming (I actually ran a couple of successful RPG adventures in the setting using Twilight 2000). More recently Steve Blease has resurrected the idea with his England Prevails blog, which has some great mocked up late 1980s news reports.
Winter of '79 looks at the potential for civil unrest in a slightly earlier period, following the Winter Of Discontent and the fall of the Callaghan government and the election of Margaret Thatcher. It's a plausible premise which lends itself to using early Cold War and Falklands-era figures, and the late 1970s/early 1980s setting lets you draw on TV shows like The Sweeney, The Professionals or the more recent Life On Mars for inspiration for more urban, low level police action.
Heading the other way, the sadly short lived Un-Tied Kingdom blog brought the idea bang up to date, positing a civil war resulting from the 2010 hung election. Not much there by way of actual gaming since the creator decided to switch scale mid-project from 20mm to 28mm and hasn't posted in the 6 months since. But there's plenty of interesting background and analysis to make it worth a read.
So how could we work up a hypothetical English Civil War in a Victorian/Steampunk era? It turns out to be quite an easy fit. Following the death of Prince Albert in 1861, Queen Victoria withdrew from public life to mourn. Her absence encouraged a rise in republican sentiment, including one wag who posted a sign on the gates of Buckingham Palace stating "these commanding premises to be let or sold in consequence of the late occupant's declining business". Victoria did continue to carry out her constitutional duties during her self-imposed isolation, but if she hadn't, this would potentially have led to a constitutional crisis. As it was, the scandal over her close relationship to John Brown, and the formation of the French "Third Republic" led to an atmosphere where in 1871 there was a republican rally in Trafalgar Square calling for Victoria to be replaced.
If we take the VBCW approach and look at potentially colourful elements we can throw into the melting pot, an 1870s Civil War has much to offer. The Cardwell Reforms (1868-1874) was a number of measures put in place to modernise the British Army which was still mired in the practices put place from Wellington's day. This gives us a good rationale for disgruntled officers choosing to join the "rebels". It also withdrew British troops from self-governing colonies, which would see a lot of colonial troops returning to the homeland. In reality the black Home Service helmet wasn't adopted until 1877, but if we bend the timeline a little and pull that date forward, we can hypothetically rationalise a wargame with Crimean era shakos, colonial sun-helmets and black Home Service helmets all on the same table.
The year 1871 also saw the legalisation of Trade Unions, and this era was a time of labour unrest, so we can bring in Union backed forces. More radical groups could easily see the formation of irregular "workers militias" agitating for even greater reforms.
The House of Saxe-Coberg-Gotha on the continent would not let their most prominent monarch be deposed without lending a hand and combined with states allied through the marriages of Victoria's daughters, could lead to the presence of foreign interventionist forces from all over Europe, including Germany, Belgium, Portugal and Bulgaria to name but a few. On the Republican side, it's certain the French "Troisieme Republique" would send aid and forces to their British counterparts. And don't forget our old hypothetical Fenian friends, equipped in freshly surplus ACW gear, who would be fighting for independence from the crown.
That's just a very short, broad overview of the possibilities, but it's certain that this "Winter of 187x" has just as much scope for colourful wargaming as its later counterparts.