Helly Hansen L/S Stripe Crew (£30.00)
Kerry says: There's a reason why this baselayer with the distinctive stripes down the arms has become one of Helly Hensen's best known and biggest-selling pieces of kit: it works. It's small and lightweight (you can scrunch it up into a ball the size of your fist) but despite it's diminutive size it's extremely warm, its thermal qualities ensuring that in weather like this weekend's freak cold snap it'll keep your core well insulated. Two other key features: flatlock seams which cut down almost all chafing; and wicking which moves moisture away from the body to keep you dry and comfortable. Thirty pounds very well spent, I'd say.
Buy yours on the Runner's World Store!