They beat Three Bridges on the final day of the season, thanks to a 76th minute James Cottee effort, but finished just a point off the play-off places after Faversham Town sneaked above them with a 4-0 home win over Kent top five rivals Hythe Town.
Luke Harvey after 11 minutes, a Charley Robertson penalty five minutes before the break and then Harvey again on 63 minutes and Josh Stanford a minute from time were the home marksmen.
Hythe lost third place to Worthing as a consequence of that defeat and the Rebels` 2-1 win against Ramsgate in front of 561 at Woodside Road.
Jordan Maguire-Drew opened the home account after 12 minutes and Harvey Sparks added a second 10 minutes before the break, with Kane Rowland reducing the arrears on 66 minutes.
Hastings United were looking to profit from Casuals` misfortune and a win at the Pilot Field against Herne Bay would have clinched a top five spot.
But Bay failed to read the script and, despite Sam Cole giving Hastings a 43rd minute lead, the majority in the 570 crowd went home disappointed after a Sam Cruttwell own goal and then Danny Walder right on half-time sealed a 2-1 win for the visitors and heartbreak for United.
Runners-up Dorking Wanderers will host Faversham in the play-offs on a bit of a downer after losing 5-1 at home to South Park.
However, they did make changes with the play-off semi-final in mind, but goals from James McElliogott and then Dan Moody with two, Dean Lovegrove and Dylan Merchant gave Park a nap hand, with Kevin Terry replying.
The opposite end of the table had already been settled, but Whitstable Town managed to move off the foot of the table after back-to-back wins, this time against poor travellers Guernsey.
After David Rihoy had given the Channel Islanders a 31st minute lead at the Belmont, Charlie Smith on 39 minutes and then a Stuart King brace on 50 and 68 minutes earned the Oystermen a second successive win.
Peacehaven`s awful campaign ended with a 4-0 defeat at Colston Avenue at the hands of Carshalton Athletic, whose Mickel Miller bagged a brace, each one sandwiched by Andy Jones and Michael Campbell.
The other relegated side, Walton & Hersham, went down 3-1 at Stompond Lane to East Grinstead Town, for whom Trevor McCreadie from the spot, Danny Leonard and Jake McIntyre were on the mark – Gareth Chendlik for the Swans.
Champions Folkestone Invicta made it to 114 points in a marvellous season after a 3-1 success against Tooting & Mitcham United in front of 508 at the Fullicks Stadium.
Harry Smith after five minutes gave Invicta a lead that Sol Patterson-Bohner levelled on 24 minutes. An Ian Draycott penalty two minutes from time restored the title-winners` advantage and Carl Rook added a third in stoppage time.
Elsewhere, Chatham Town went nap away at Whyteleafe with Luke Medley netting a hat-trick and Austin Edwards and Liam Hickey singles – Shawn Lyle and Sam Clayton replying for `Leafe.
There was only one goal at Chipstead as Jordan Cheadle`s 72nd minute effort sealed victory for visitors Walton Casuals.
Reis Stanislaus gave Molesey a 63rd minute breakthrough at Sittingbourne but the hosts battled back to level through sub Tom Brunt two minutes from the end.
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