Though I can't speak for Reuters, newspaper men like Horace Greeley, James Gordon Bennett and others would send out fast ships to loiter outside ports and look for ships coming from Britain to get a jump on the news.

This might seem like a trivial advantage, but you have to remember that ship arrival times, especially before grand Atlantic steamers could take months and their arrival times could varry by days or weeks due to storms and what have you. Due to this a ship could rarely just sail into port, they would wait on a dock to become available which could take hours or days. During this time your men could sail up to the ship and buy newspapers from Europe, sail back to port and begin copying it for print. The process of setting up a printing press could take over an hour per page, and there weren't really set times for when the paper came out.

This system didn't last very long as the competition was fierce and the costs huge. Telegrams and fast steamers with reliable travel time made the system obsolete. Many newspapers ended up pooling money together to create organizations like the Associated Press to share news and increase profits for all.