He was sponsored by the
Robert Spencer, 2nd Earl of Sunderland for eighteen years, for whom he served as an under-secretary. On 19 December 1706, Mountstephen was at Brown's Coffee House, King Street,
Westminster in the company of other MPs when he took out a razor from his pocket and slit his throat. His suicide was probably because it became public about his passing of state secrets to the
King of France, in return for a pension, although there were rumours that he took his life after his proposal of marriage was rejected by someone of higher social standing. ==References==