If there’s one bit of kit I’d massively recommend for anyone who likes trail running, it’s a down jacket – despite the fact you will almost certainly never actually run in it. Why? Super-warm and incredibly compressible and light, it’s the perfect thing to chuck in a bag for a long run so you know you have something warm to put on afterwards or if you need to stop running due to injury or getting lost. Just knowing I have a jacket that can keep me warm down to near-freezing temperatures gives me a lot more confidence running off into a national park alone, believe me!
And it’s the perfect thing to wear on the train to your jumping off point, particularly when leaving early on a cold, dark October morning, and then just squash into your bag (ideally inside a small dry-sack) and off you go. Mine is a very cheap one from Decathlon. The quality might not be quite up there with Patagonia or North Face but it’s hard to argue with a down jacket at less than £30. Actually it’s quite hard to argue with a down jacket at all as their grasp of logic is very basic.