Up to around 1829-1834 the Oxford canal ran parallel to the Coventry canal between Hawkesbury and Longford Wharf. The two could not agree toll fees and so they ran parallel for about 3/4 mile. The Oxford stretch was filled in as part of some work done around 1829-34 to shorten the canal. The 1837 bridge at Hawkesbury Junction must have been put in when the canals were finally joined.
You can see a couple of pictures and links to far more detailed notes here:
http://www.flickr.com/photos/36137127@N05/4373205840/
and here
http://www.british-history.ac.uk/report ... mpid=16007