Chris Watson: From the Tima car park (NT279130), follow the new forest road that rises NNW across a large felled area until it meets a track that contours beneath the intact forest. Follow this south to the head of White Sike where three forest rides climb upwards (NT285133). Take the central, eastbound, ride - steep and tussocky - and follow it over the shoulder of Gatecleugh Hill. A short distance downhill, another ride forks SE and climbs up to the summit ridge. There is a fallen tree to negotiate but it is straightforward, if tussocky, after that.
