 With relations between the MR and the LNWR deteriorating , Watkin turned his attention to the proposal to link to Aylesbury . Negotiations between the A & B and the GWR had broken down , and Watkin seized an opportunity to agree running rights over the A & B 's route north from Aylesbury , taking over the line completely in 1891 . In 1888 work began on the extension to Aylesbury . 
