I tried stripes of two rows in each of two colours first. It gives a nice tweedy effect.
The other version I tried has one row of each colour (and I think that was the stitch pattern I was trying to match). To alternate the colour after each row, you need to use a circular needle. One colour is always at the wrong end of the row when you want to use it, but with a circular needle, you can just slide the knitting along the needle and knit two consecutive rows in the same direction.
Moss stitch has the advantage of being exactly the same on both sides, and also lies flat, unlike stocking stitch, so it's useful for scarves and the like. Both of these striped moss stitch patterns would be nice in a scarf - the one row stripe has the advantage that both edges are similar, whereas in the two-row stripe, one edge has loops at one edge where the colour not in use is carried over two rows of the other colour.
A stitch I have previously considered for multi-coloured scarves is linen stitch. It lies flat, both sides are attractive (though not identical), and it looks good in narrow stripes. But I have only tried swatches of linen stitch, because it is very slow to knit. Moss stitch grows much faster, though slower than stocking stitch. Worth trying.
And back in John Lewis, I did find a nice pair of jeans - reduced, too.