Political career and peerage
In the 1886 general election, Williamson was elected to the House of Commons as Member of Parliament (MP) for Lancaster, and held his seat at the 1892 election.
Williamson was a strong supporter of Prime Minister William Ewart Gladstone, the Liberal Party leader, and Gladstone likewise held Williamson in high regard for his business instincts. Williamson was a supporter of Gladstone's Government of Ireland Bill 1893, and gave generously to Irish causes. Gladstone planned to recommend Williamson for a peerage but resigned in 1894, without any outgoing honours. The next year, though, Williamson was elevated to the peerage as Baron Ashton, of Ashton in the County Palatine of Lancaster, during the Prime Minister's Resignation Honours of Lord Rosebery.
Williamson's peerage was one of two in Lord Rosebery's honours list that led to heavy criticism, including from the Duke of Devonshire, head of the Liberal Unionist Party, who insinuated that Williamson had bought his title. Lord Rosebery explained that the creation of the two peerages were a "point of honour" as they had been promised by Gladstone, and added that the idea they had been sold was "an infamous lie." Williamson, now Lord Ashton, exclaimed that he had not "paid a farthing" for his title. Nevertheless, the accusations that Ashton had purchased his title continued, and he was subject to frequent criticism and derision in Lancaster, which led to his eventual withdrawal from public life.
Prior to the January 1910 general election, Lord Ashton sent a letter to the electors in the Lancaster Division promising that there was no connection between his politics and philanthropy, but that if the charges continued against him, he would withdraw his support from Lancaster. He followed through with his threat the next year, after insulting incidents related to the 1911 municipal elections, and he cancelled all his significant charitable interest in the city.
Lord Ashton's withdrawal as benefactor caused considerable dismay among the various causes he had supported in Lancaster. In response, the Lancaster Town Council passed a resolution "expressing gratitude to him for his benefactions to the town and detestation of the attacks to which he had been subject." Lord Ashton was unmoved, however, and transferred his philanthropic efforts elsewhere, particularly to the East End of London. During the First World War, he backed the War Loan, with £3,000,000 in cash (equivalent to £169,540,000 in 2025). He also continued to support the Liberal Party.
In 1920, Lord Ashton was made Constable of Lancaster Castle for life. He was also Deputy Lieutenant of Lancashire and was elected as president of the Lancashire County Cricket Club in 1927.
In later years, he became a virtual social recluse, although still running his business interests. He divided his time between Ashton Park and Ryelands House, his other home in Lancaster. Ryelands became packed with stacks of newspapers and magazines that reportedly reached the ceiling.
When in London, he refused to stay at his townhouse, Alford House, instead staying at a hotel. He would not go to social events or pay social calls, and refused to see anyone who had not made an appointment to see him. He even refused to meet a journalist from South America who had travelled to interview him but had mistakenly not arranged the appointment in advance.
