Mr Patch was a plumbing apprentice for less than a year before the Great War broke out, and he returned to the profession after it ended.
The 111-year-old was awarded the Fellowship of the Chartered Institute of Plumbing and Heating Engineering honour on his birthday last month. He said he would rather be remembered for being a plumber than a soldier.
The citation for the fellowship said: 'For the worldwide respect Harry has earned as a national hero and ambassador for his country.'
Mr Patch wrote about his life in the industry and during the war in his book, The Last Fighting Tommy. During his plumbing career he undertook installations across the South West, including the Wills Memorial Building that was opened by King George V on June 9, 1925.
Blane Judd, chief executive and secretary at CIPHE, said: 'The whole nation had huge respect for Harry and we felt it was only right that we should recognise his long service to our industry and the country. The plumbing profession has lost a great elder-statesman.'