The leaders took a while to get into their stride, then raced clear by scoring six tries with fly half Mark David gaining a try, five conversions and a penalty goal, while skipper Karl Hocking notched his 116th league try.
The Old Parish also ran in tries by flanker Marcus Sainsbury, wing Gareth John, centre Alun Brown and wing Gareth Holmes, while fly half and skipper Stuart Morris placed three penalty goals for the Athletic in a game well controlled by Clayton Thomas.
Glamorgan Wanderers remained in third place despite beating UWIC 36-12, but are now just one point behind Llangennech with a game still in hand and a better try-count.
No 8 Emyr Christopher had an outstanding game and he, Mark Heywood, Dave Willey, Lee Mullane and replacement scrum half Gareth Spain went over with Heywood converting one and landing two penalties and Jason Pocock also placed a penalty.
The students ran in tries by Rhys Edwards and Gareth Dacey and Phil Dolman converted one.
Blackwood battled their way to a 25- home win over Builth Wells and went out of therelgation zone, moving over Fleur de Lys, Carmarthen Athletic and UWIC in the process.
Fly half Jeremy Lloyd led the way with a penalty, drop goal and two conversions and tries came from Jamie Sims (2) and Christian Perry, while Rob Lloyd placed a lone penalty for Builth Wells.
Bonymaen jumped from seveth to fifth place after a 30-0 win over Tonmawr, who now are staring relegation in the face and have eight game to survive, but are already 13 points away from safety.
Scrum half Gareth James, formerly of Penygraig, notched four of the five tries by the Parc Mawr club and wing Chris Griffiths also crossed with Anthony Evans placing a penalty and conversion.
The Half a Game initiative is currently sweeping across Wales and proving a major success. The scheme aims to give every young player at least half a game every weekend. WRU TV recently visited a festival in Narberth where clubs have fully embraced the initiative.
Both Bargoed and Swansea were seeking their first win of the Principality Premiership season this afternoon. It proved a fruitful day for the hosts - not only did they win, but Bargoed claimed a try bonus point.
Cardiff managed to keep their unbeaten record at home intact, but only just as Bridgend made them work extremely hard before the Blue and Blacks secured a hard fought Principality Premiership win at the BT Sport Arms Park last night.
Former Wales back row Andy Powell gives a guided tour of The Wern, home of Merthyr RFC, who are determined to prove a lot of people wrong and make their mark in their first season in the Principality Premiership.
Wales Sevens head coach Gareth Williams looks back on the Rio Sevens success where he helped GB win silver. He believes the successful campaign is a huge boost to his Welsh squad as they prepare for another World Series, as WRU TV's Graeme Gillespie discovers
British and Irish Lions head coach Warren Gatland will be heading back home to take on the All Blacks next year where for him, success for 2017 is all about going to New Zealand and winning a Test Series.
Last week all roads led to Eugene Cross Park where defending champions Ebbw Vale hosted this season's launch of the Principality Premiership. WRU TV's Graeme Gillespie was there to capture the thoughts of Damien Hudd, captain of Ebbw Vale, and WRU Head of Performance, Geraint John.
Llandovery made it three in a row when they defeated Aberavon in the final of the National Foster's 7s at BT Sport Cardiff Arms Park on Sunday. On another eventful day of sevens, Newport claimed the Plate and the Dragons won the women's crown
Last week saw Cardiff welcome players from around the world for the 21st Golden Oldies Festival. The tournament features players over 35 years of age, and this year's event saw a select few represent the WRU in a 'friendly' against the Wooden Spoon.
Wales Under 18 captain Callum Bradbury is delighted to have seen his side claim a narrow 18-17 victory against a strong SA Schools 'A' side to end the three-match Under 19 International Series in South Africa on a high note.