Following the success of the Aveling and Porter business, Thomas rose to local prominence, first on the council and then between 1869 and 1870 as Mayor of Rochester. Politically he held rather radical views within the Liberal Party. Not surprisingly (given the location of the Invicta Works) he was a strong advocate of improving the river bank at Strood, which was at that time marsh. As mayor he took an interest in the significant local charity Watts' Charity and was appointed to the board of trustees in 1871. He helped lay out the public gardens in Rochester Castle, sat on the Rochester School Board and was a governor of the Sir Joseph Williamson's Mathematical School.