The annual circumnavigation of the town brought a big turnout for Garden City Runners.
The Welwyn Centenary 20.20k uses the centenary path round Welwyn Garden City and there were 65 from the club taking part.
Peter Harvey said: "There were four staggered starts according to expected finishing time and this year the runners went anti-clockwise.
"Conditions in Commonswood were certainly slippery and the big hill up to The Ayots was tackled deep into the run."
New club member Bradley Birch was first home in one hour 25 minutes 27 seconds followed by Harvey, just under four minutes later.
Herbie Hopkins was also under 90 minutes and would have finished second but for lack of course knowledge taking a diversion near Tewin.
Anna Lillie was the first woman in 1:57:37 closely followed by Veronica Shadbolt with no others beating two hours.
Brad Smith pushed a buggy with two-year-old Linden, taking 2:22 while Peter Jasko ran the route clockwise before going anti-clockwise, doing 2:19 for the second loop.
Kath Evans headed west once again for the South West Coast 50k.
Starting in the shadow of Dunster Castle, the route took in Minehead and Porlock, even if a climb up to Dunkery Beacon was re-routed due to the wind.
Barbara Kubis-Labiak completed the London Triathlon, based at the Excel.
She clocked 43:29 for the 1500m swim in Victoria Dock, 1:26:11 for the 40k bike ride to Westminster and back, and 55:32 in the 10k run.
That made a total time of 3:16:18.
The parkrun highlights saw 94 from the club running somewhere in the globe.
Most of them stayed local at Panshanger at the 400th event, where parkrunners and parkwalkers were back on the standard course.
Tom Buzzard was fifth, Adam Wadley seventh, Paul Guy eighth and Martin Mitchell 10th in a course PB of 19:59.
For the ladies, fifth, eighth and ninth places went to Rebecca Barden, Rebecca Cullers and Felicity Wadley.
Chris Dungate achieved a new course PB at St Albans where he finished ninth, and there was a new course PB for Helen Stafford at Tramore in Watford, good enough for third lady.
Juliet Vine was first lady at Jersey Farm and Lucy Iles fourth lady at Clevedon Salthouse Flats.
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