Whilst it's obviously one of our more trivial concerns in the general scheme of things the OS is actually completely wrong.....someone travelling from Southampton wouldn't touch the M4 (other than driving over it on the A33, having left the M3 at Basingstoke)
http://www.multimap.com/maps/?qs=reading&countryCode=GB#map=51.45499,-0.96926|10|4&bd=useful_information&loc=GB:51.45499:-0.96926:14|reading|Reading, Berkshire, England, RG1 2