Ballynahinch will face a relegation/promotion play-off at Ballymacarn Park on Saturday, May 3 after a 27-13 defeat by Clontarf left them finishing second from bottom of the table.
On the other side of the coin, Dublin side, Clontarf, were celebrating as they were crowned Ulster Bank All Ireland League champions after favouties Old Belvedere lost suprisingly 23-18 to relegated Garryowen in what proved to be a dramatic end of season game.
Hinch, who only achieved promotion to the top tier of Division One will now face Connacht club, Buccaneers, in a winner takes all match with a place in Division 1A the prize.
The Co Down side went into the game knowing their recent form - five wins in a row, three of them with try scoring bonuses - could still see them get out of trouble if they won again and Dolphin did not pick up a losing bonus point at home to Lansdowne.
The Corkside lose, but did secure a losing bonus, so even if Hinch had produced the second shock of the day in beating Clontarf, it would have been in vain.
Derek Suffern’s side, who had recently retained the Ulster Senior League championship title, started strongly and opened the scoring with a penalty from Richie Lobb.
But with the title on the line, Clontarf were soon finding their rhythm and a converted try and a penalty had them 10-3 ahead.
David Joyce and Lobb exchanged penalties before the break to make it 13-6.
Four minutes into the second half Aaron Cairns’ try and Lobb’s touchline conversion levelled matters.
But that was to be the end of the Hinch resilience as it went into the final quarter.
Two tries from former Irleand U-20 international, Peter du Toit and Joyce;s trusty boot got ‘Tarf over the line - and landed the title.