Sometime about 1840 the Lincoln architect W. A. Nicholson made extensive alterations to the east end of the Stonebow, when the building that housed the old City prison was pulled down.Nicholson 1842, pp. 89–9Hill 1955, pp. 6–7 Nicholson observed that the Roman wall of the Lower Colonia in Lincoln was to the north of the Stonebow and was still standing to the height of about 15 feet. This suggests that the Stonebow was a barbican, that had been built forward of the Roman southern gateway. Nicholson appears to have been the architect responsible for the present building to the east of the Stonebow completed about 1844 which now contains the Mayor's Parlour and the display of civic regalia. Further alterations took place 1885–90 by the architect J. L. Pearson, who was responsible for alterations on the west side of the Stonebow. Pearson created an additional passageway arch and the shop units under the arch. In connection with the alterations Potts of Leeds provided a new clock in 1889 with two dials (one facing north, the other south).
