Fowler's consulting work extended beyond Britain including railway and engineering projects in Algeria, Australia, Belgium, Egypt, France, Germany, Portugal and the United States. He travelled to Egypt for the first time in 1869 and worked on a number of, mostly unrealised, schemes for the Khedive, including a railway to Khartoum in Sudan which was planned in 1875 but not completed until after his death. In 1870 he provided advice to an Indian Government inquiry on railway gauges where he recommended a narrow gauge of for light railways. He visited Australia in 1886, where he made some remarks on the break of gauge difficulty. Later in his career, he was also a consultant with his partner Benjamin Baker and with James Henry Greathead on two of London's first tube railways, the City and South London Railway and the Central London Railway.