In 1841 he built the first of three new Mill Hill factories, a bold venture, as the mill was said to be huge, and the cotton industry was then in depression – a fact which was mentioned by the Prime Minister (Sir Robert Peel) in the House of Commons as evidence that persons did not hesitate to employ their capital in the further extension of the cotton trade, notwithstanding its condition.
Thomasson was intimately associated with Richard Cobden in the repeal of the Corn Laws and was a good friend of John Bright who attended his funeral and bore testimony to his remarkable capacity as a man of business, saying, "He will be greatly missed by many who have been accustomed to apply to him for advice and help.".
On an occasion in the Bolton Theatre, when the Corn Law question was contested, he may be said to have called Abraham Walter Paulton into public life, by sending him on to the platform to defend the cause of repeal.
Thomasson's indignation had been greatly excited under the old government when it was usual to call out armed police, or the military, for comparatively trifling disturbances.
For some time he was a member of the Board of Guardians, but resigned because he "could not sit and see men slaughtered by a stroke of the pen," alluding to what he considered the illiberal manner in which relief was dispensed.
He subscribed fifty guineas towards a memorial statue of Samuel Crompton, the inventor, and proposed that something should be given to his descendants, saying: "If Crompton had been a great general and had killed thousands of people, the Government would have provided him with a small county, and given him a peerage; but as he had given livelihood to thousands of mule spinners, it was left to the people to provide for his distressed descendants."
After Mr. Thomasson's death there was found among his private papers a little memorandum of these advances containing the magnanimous words: "I lament that the greatest benefactor of mankind since the invention of printing was placed in a position where his public usefulness was compromised and impeded by sordid personal cares, but I have done something as my share of what is due to him from his countrymen to set him free for further efforts in the cause of human progress."
When in London, he would, two or three years in succession, call in Fleet Street at a publishing house – then aiding in the repeal of the taxes on knowledge and defending the freedom of reasoned opinion — and leave £10, bearing the simple inscription, "From T.T."
Workmen whose views he did not share would invite lecturers to the town, whom he would sometimes entertain, and judging that their remuneration would be scant, he would add £5 on their departure to cover their expenses.
Thinking that Thomas Huxley might need rest which his means might not allow, Thomasson offered to defray the cost of six months' travel abroad with his family.