Castle popped up in the right place at the right time to receive a pass from emergency scrum half Gareth James to drop the goal that turned what looked like being a one point defeat into a dramatic victory.
There was just enough time for gallant Abercarn to re-start, but there was never going to be a seventh change of lead before the final whistle after they knocked-on as they chased the kick. That left Division 1 West outfit Ystalyfera with a dream ticket to the home of Welsh rugby on Sunday, 16 April and a final against Penallta.
Abercarn picked up a penalty try and had four penalties from outside half James Baker to go with it before full back Jason Evans dropped a goal to make it 22-21 with time running out. Matthew Scott and Steffan Jones crossed for tries for Ystalyfera, James converted one and kicked two penalties and Castle also kicked a penalty before his drop goal heroics.
In the other semi-final, Penallta just did enough to reach their third final as they beat Nant Conwy 18-13 in a repeat of the 2011 final. Last year the Pitmen were beaten by a last minute drop goal at the Principality Stadium against Bedlinog and they will be gunning for revenge next month.
Ospreys academy and Bridgend outside half Joe Scrivens was the hero for Penallta as he ran in a try and in a 13 point contribution to go with a try from Cory Tucker. Nant, the Division 1 North leaders, led 10-6 at the break, but were overtaken in the second half.
Scrivens broke clear to score the try that put Penallta ahead at Newtown and then Tucker put them further ahead. To their credit, Nant pushed hard to the end and Delwyn Jones kicked eight points to go with Tom Oliver’s try.
WRU National Plate Semi Finals
Abercarn 22-24 Ystalyfera
Penallta 18-13 Nant Conwy
