A few of my reasons for modelling 1840s railways in HO:
1. I like microlayouts! In the early 1840s most trains were short (many mainline trains only had four carriages at this time, and even that could be a strain for some of the low-powered locos). And an HO layout takes up just three-quarters of the area of an equivalent OO layout, which helps as well. The photo for this post shows my attempt to answer that age-old question "Can you build a station on an A4-size baseboard?" The mock-up suggests the answer is yes, if the footprint is 23 x 4 inchs and you use a traverser at one end. So anyone with a 48 x 12 board can really let rip!
2. There's some stock available. In the photo I've used the Bachmann 4-2-0 Norris locos (the prototypes were used on the Birmingham & Gloucester, Aberdare and Taff Valley Railways and then sold on to collieries, contractors etc in the 1850s) to test clearances. The coaches are also by Bachmann (the "Prussia" coach from the Potsdam Railway: broadly similar to British coaches of the time, but if there's interest I'd add a post on how to Anglicise them). The figure are by Prieser, who also make nice horse-drawn carriages and carts for the period,
3. Track is easy, especially if you aren't a rivet counter. Most early railways used versions of flat-bottomed rail, so I've used Peco streamline points in my mock-up. Sleepers are likely to be completely hidden in this period as ballast was usually laid above the tops of the sleepers, which does open up new approaches to ballasting. Much to my initial surprise the short wheelbase Norris locos will run over a series of three small radius Streamline points in succession without a hiccup.
4. Early locos had low-slung boilers (due to the pioneer engineers' concerns about stability), and this gives them a rather "broad-gauge" appearance when viewed from the front. As a result OO models of early locos can look a bit top-heavy, even to someone with my coarse-scale eyesight. However HO has the advantage of true scale distance between the rails, so that the locos and coaches match the proportions seen in early lithographs and photos.
5. I like the challenge of modelling early railways (although there's actually a lot of info available if you're into historical research), and I like the challenge of modelling more modern British railways in HO as well. In both cases you need to use a bit of ingenuity and you will learn to appreciate anything that can be pressed into service. Combine the challenge of a minority scale (for British modellers) and a minority era, and you need never be bored again!
And why am I trying to fit a station on a piece of foamcard 23 by 4 inches? I just fancied a station and fiddle yard that would fit on a desktop!