I think a 4F and four Mk 1s might look a little out of place!
Paul
Reminds me of an article in RM about garden railways in the 70s, where the owner of the lines (yes plural) all fairly short, indulged in different scales, and supported the theory of impressionism when it came to garden railways - that has stuck with me, although I read the article at least 20 years before I started playing trains in the garden.
There is one drawback - his lines were all, more or less, at ground level, and the natural scenery was an innate part of the railway(s).
I have always preferred a ground level line, but because I am an inveterate tail-chaser, I have installed them (all two of them) at the edge (ish) of the lawn, which makes a natural boundary to the planting. Sure the triffids will have a go, but the natural delineation allows you to take a stand of 'thus far and no further', and get vicious with the secateurs.