I was planning to wait until the winter, when the leaves were off the trees, but as I'm in often in these woods, thought I'd give it a go. To my surprise, my GPS seemed quite happy under quite dense tree cover - its a Garmin Venture Cx, so not even a 'high sensitivity' receiver. Was getting between 20 and 30 foot accuracy, which whilst not ideal, is okay after multiple readings (and I'm in these woods a lot!).

Compare this with the weekend, when I was trying to map some footpaths around East Hendred, when the wretched GPS wouldn't get a decent fix at all -- it had 5 satellites, but only reported 150 foot accuracy (useless). At its best, this unit reports 6-foot accuracy, which is great - but you do need open skies. I guess the time of day I was mapping at had poor satellite coverage. I wasn't even under any real trees, just the odd hedgerow.