He was president of the Bilton Ward Conservatives, a member of the Knaresborough Board of Guardians and an alderman of West Riding County Council.

In spite of his "spectacular success" as a developer, Simpson suffered a financial embarrassment, known as his crash, a few years before the First World War, and lost possession of Oakdale, Although he compounded the situation by going on a sea voyage to New York City and leaving his son to deal with his catastrophe, he retained business confidence, remained a member of the council, and was made freeman in 1923.

[10] The second son, Lieutenant George Simpson (1892 – 23 August 1918),[nb 4] of the Australian Infantry (AIF), and a farmer in peacetime, was also killed in action at the Somme.

[1][nb 5] In 1891, Simpson was describing himself as a builder and contractor, and was living with his wife, son James, and father-in-law George Holmes at 4 St Mary's Walk.

He always aimed at dignity and variety, and the preservation of amenities, holding that it was these features in development which gave character and distinction to a town.

"It was rumoured that the exuberant carvings and spires on the main façade were included to provide employment for masons who would otherwise have been affected adversely by the current building recession".

[16]: 519–520 Simpson was respected in Harrogate as a businessman who had achieved "spectacular success", but he suffered a major financial embarrassment due to unfortunate investments between 1909 and 1911, This was not spoken of by his contemporary admirers, but was nevertheless known as his crash.

By July of that year he was known to owe £858 8s 7d (equivalent to £117,973 in 2023) for Harrogate and Pickering rents, and he was issued a distraint for goods from Oakdale.

However, although his Harrogate office continued his business, he soon moved again, to Bury St Edmunds, returning to the town at the end of 1916.

The Yorkshire Evening Post said:[17] During his lengthy service on the Council [Simpson] probably did more than any other man to establish Harrogate as a leading health resort by his unremitting care and attention to the welfare and government of the spa ...

[17][4] When Simpson fled the effects of his crash in 1909, he departed from Liverpool with his wife on the RMS Lusitania, listing their home as the mansion Oakdale, although they were about to lose it to pay debts.

[22][nb 8] In 1926 they returned on the RMS Windsor Castle from Durban, South Africa to Southampton, via Port Elizabeth, Cape Town, Madeira and East London, arriving on 15 March 1926.

[23] Following a long illness which had made him an invalid, Simpson died, aged 71, on 15 January 1931, at his home, 36 Rutland Road, Harrogate.

[17][20][nb 9] Simpson's funeral took place on 17 January 1931 at St Wilfrid's Church, Harrogate, and he was interred at Grove Road Cemetery.