In 1858, a very decrepit Burgh House was taken over by the Royal East Middlesex Militia. It served as the headquarters and officers' mess, while sergeants and bandsmen moved into a new building on Willow Road (now known as Willow Hall). Two new barrack blocks were erected in front of Burgh House, with a high wall continuing along Well Walk.
The Militia was an independent army, which formed and reformed whenever a French invasion appeared imminent. The rank and file were called up every summer for training – which mostly consisted of drilling and rifle practices on Hampstead Heath. This, along with their anti-social behaviour when off-duty, became a big problem for the local community. In 1880, when it was proposed that Burgh House might become the new brigade headquarters, there was such a substantial local outcry that, in 1881, the Militia left Burgh House for good.