A4130 into Henley. 5.25miles through some lovely Bucks countryside - although not if you're stuck behind a lorry having problems - and nowhere to get by! Traffic was tailed back as far as the eye could see. Average speed works out at 26.25mph, slowest speed I recorded was around 14mph. Even travelling at well below the limit. the driver seemed to rely heavily on his brakes - I noticed a strange burning smell all the way but the blue smoke belching out on that final descent gave it away.