Pulborough secured their London 3 South East safety and climbed up to eighth place with a 15-7 victory on the final day.
There was all to play for going into the last day with Seth Wise’s side still mathematically facing the possibility of relegation.
Despite a damp first-half showing, Pulborough secured the win they needed to retain their place in the division after promotion last season.
It was all fairly comfortable in the end with Boro finishing two places and nine points ahead of Park House, who took the third and final relegation place – compounded by fourth-from-bottom Gillingham’s win over Bromley.
Pulborough captain Seth Wise said:“It was a great day to be a Pulborough player, it really was one of those days that rugby players live for.
“The character that was shown by our team to keep themselves in the game and then turn a disappointing first half around and really step things and put away a committed and aggressive side was exceptional.
“The emotion was definitely there at the end, but I think the overriding feelings were relief and probably satisfaction. Relief at securing our place in SE3,
“I’ve said it before, but it really would have been a travesty for this side to have been relegated.
“We’ve come to the end of a two-season journey where we’ve been hugely successful. The challenge now is to kick start the next chapter and build on this success by growing our squad and achieving the consistency needed to compete in the top half of this league.
“With our achievement and those of the third and second teams, who have both been promoted, this really is the most successful season the club has ever had and it’s been an absolute pleasure to be a part of it.”
Gifting away possession and sloppy kicking allowed the Park House 10 to continuously pin Pulborough in their own half with his thundering boot.
The first score came out wide as the hosts flanked the defence to score in the corner. A Tom Hoey penalty was Pulborough’s only points of the first as they trailed 7-3 at the break.
In the second half, Pulborough dominated and with the first of three Park players seeing yellow, Dan Paige used his pace to cross the line.
With 10 minutes to go, Frazer Oliphant-Hope chipped a beautifully-weighted kick for Simon Burfiend to collect to seal the victory.