In Volume 1 of The Confidential Guide to Golf Courses, Tom Doak published that.

“These small, dirt-cheap nine holes within the Musselburgh Raceway are in fact the oldest documented golf course in the world. Between 1874 and 1889 it hosted The Open Championship six times, while also serving as home for the Honourable Company of Edinburgh Golfers and Royal Musselburgh Golf Club. But its nine holes could not accommodate the growing demand for golf, so the links were abandoned by those clubs in the 1890’s for greener pastures in the more affluent suburbs, and for years the Old Links survived only because it was the infield for the racecourse; it was almost paved over for development in 1985 before public outcry saved it and some money was raised to fix it up.

There is still some good golf here, most of all the long par-4 4^th with its green in the far corner of the links, and the road dangerously close at hand. Mrs. Forman’s pub behind this green was golf’s first half-way house – they served golfers drinks through a window in the wall – and it was there that Old Tom Morris had to take refuge from a hostile gallery during his match with Willie Park Sr. in 1882. Every golfing visitor to East Lothian should stop in here to pay homage to the humble beginnings of the game.”

The Old Golf Course at Musselburgh Links received a score of 4 out of 10 from Tom Doak.