The Ballad of Buster Scruggs, perhaps the Coen Brothers’ last collaboration, features countless horses and a couple of legendary actors. Both – as Irishmen around since the 1950s – would know of the Cheltenham Festival, or at least of what it used to be. Brendan Gleeson plays a bounty hunter in the final leg of the anthology, the theme of which is mortality. Liam Neeson is cast as an ageing impresario with an artist called Harrison, a young man with neither an arm nor a leg – which would not be much good at Cheltenham prices these days.  The pair…