This route is really an extra section to the Ashby-De-La-Zouch to Melton Mowbray route.
Starting from Melton Mowbray. find the B6047 (Dalby Road) and head south, after 11 miles or so you will come to a junction with the A47 (another great road to Peterborough) turn right and then left and your back on the B6047. Follow this road until to reach Market Harborough.