Due to an escalation of the persecution of Christians in China, the Superior General decided that he would no longer permit their mission. On 23 September 1807, he ordered them to go to Stonyhurst College in Lancashire, England, and await further instruction. Their vessel had to circumvent the French fleet invading Portugal, causing it to run out of food and almost run out of water. They finally reached Liverpool and then Stonyhurst College on 21 December 1807. At the college, Grassi taught Italian and Latin, while studying calculus and astronomy. He also studied mathematics and astronomy at the Royal Institution in London.