When it officially opened on the 15th September 1830, the Liverpool and Manchester Railway, was the first to combine all of the elements which we now know make up a real railway service. A fully surveyed and engineered line, with cuttings (eg. Edge Hill), embankments, tunnels and bridges, numerous stations, grand termini, reliable locomotives selected by competition (1829 Rainhill Trials), carriages designed to carry passengers and all running to a regular timetable. All of the earlier attempts at steam powered traction lacked one or more of these features. My wife and I were living in Liverpool in 1979, and the city council and the then British Rail were keen to promote the celebration of the 150th anniversary of it's opening via a Railway Spectacular later that year.
This is illustrated by a photo of the British rail float in the Mayor's Show of that year.