For the first time in the 109 year history of the Welsh Rugby Union, a National League was introduced in 1990/91. As 1989/90 Mid District champions, Mountain Ash Rugby Football Club, known as "the Old Firm", was placed into Division 2 of the newly-named Heineken League.

This book details the fortunes of the club in the 30 seasons up to the end of 2019/20. The historic inaugural season, the highs and lows of the League, the WRU Cup runs in the first half of the 1990s, which saw Mount play Llanelli RFC at the Rec and also get to the quarter finals, the successes of the club's 2nd and Youth XVs, and the opening of the club's new ground, Duffryn Pennar Park, are all covered and enhanced with the use of hundreds of colour photographs.

This book is the third in a trilogy which has covered the entire history of one of the oldest and most famous clubs in the South Wales valleys. It is a must for all Old Firm supporters and those interested in the history of Welsh club rugby.