However , the only route to London was to the River Thames at Oxford , then down the river to the capital .
By 1790 , an extensive network of canals was in place , or under construction , in the Midlands .
The only route to London was to the River Thames at Oxford , then down the river to the capital .
By 1790 , an extensive network of canals was in place , or under construction , in the Midlands .