Eventually arrived at the right location after looking to the west of the A5130 and not the east! Lee Evans directions here are spot on http://bedfordshirebirding.blogspot.co.uk/2013/11/wintering-dartford-warblers-at-aspley.html
After about 40 minutes a Dartford Warbler started calling and then showed itself at the top of some gorse. I was joined by a local birder and we followed the Dartford Warbler around as it called quite frequently but showed itself only occasionally. We both thought we could here another Dartford calling distantly but neither of us could be sure. No Dartford pics I'm afraid just a really bad Green Woodpecker and a Robin to add some colour and movement to the post.