Horsham head coach Nick Stocker says they must learn to cut out the mistakes after a victory he felt they gifted to Charlton Park.
The Green and Whites had to settle for a losing point as they went down at home to a powerful side, who are aiming to return to London 1 South at the first opportunity following relegation last season.
Horsham – who led 17-13 at the break – scored through Joe Wilde, Tom Johnson and 17-year-old Jordan Bell with Johnson kicking three conversions and two penalties.
And despite having a young team which at one stage, when Johnny Ordidge had gone off injured, saw a youthful back-line containing no players over the age of 23, Stocker has stressed they must learn from their mistakes.
He said: “It was a disappointing result against a large lumpy team that didn’t create any notable chances, but scored tries from our mistakes giving good possession in dangerous position.
“There were too many missed tackles, especially in wide spaces and we need to tighten that up significantly.
“The youngsters in the team are learning that any mistake gets punished and every player needs to take responsibility to improve individually and collectively. Early injuries disrupted our pattern, but we still fashioned opportunities that weren’t taken.”
The Green and Whites led after just three minutes as good pressure from the defence resulted in a Mike Tredgett carry and Johnson kick through, which was chased and finished by Wilde. Johnson converted from wide on the sideline for a 7-0 lead.
On 10 minutes, Park scored as they crashed over from a five metre scrum following a turnover, but the conversation attempt was charged down by Nick Bell. Johnson then slotted over a penalty, before Park put one through the posts themselves to trail 10-8.
The visitors led for the first time five minutes before half-time after a number of missed tackles saw them ease through after a scrappy line-out.
Horsham however had the final say of the half as a turnover ball was snapped up by Jordan Bell to score, which Johnson converted.
Park came back in the second half and scored a pick-up and drive converted try. Johnson then scored and converted his own try after an error-strewn spell.
The game continued to twist and turn as Park went back ahead on 62 minutes after a poor clearance as they scored and converted to lead 27-24.
Two minutes later, Johnson slotted a penalty to level, but Park put down what turned out to be a winning score as their winger completed his hat-trick and the extras were added.
Horsham travel to Hammersmith & Fulham on Saturday in the RFU Intermediate Cup.
Horsham: Brady, Fisher, G.Barber, Goward, Clarkson, Smith, N.Bell, Tredgett, Walker, Johnson, D.Barber, Ordidge, Wilde, Gonzague, Palmer. Subs: Fairs, Whiting, J.Bell.