Oxfordshire were relegated to the County Championship Plate after a battling 34-14 loss to North Midlands at Chinnor.
Defeat at the hands of the pool winners was perhaps no surprise, but the damage had already been done in the first two games.
Narrow away losses against Durham and Cumbria meant Oxon needed a big win to avoid the drop from the County Championship Shield.
There was a glimmer of hope when they took a 9-0 first half lead, but this was soon squashed after the controversial sin-binning of flanker Tom Johnson (Reading).
The visitors capitalised to lead 10-9 at the break and raced clear in the second half.
Oxon coach John Brodley said: "I'm so proud of all the players and back up staff and so grateful that we've seen this competition through.
"Our performances have improved with each game.
"We knew today was going to be our most demanding fixture and we couldn't have wished for a better start, but the sin-binning of Tom Johnson was a wrong, harsh decision which cost us dear.
"That aside, the higher league experience of our guests was always going to be a telling factor and overall they deserved their win.
"The experience has done us all good.
"But I do feel that questions must be asked about the future of the competition that sees amateur players travelling the distances we have had to cover at the end of such a long and tough season.
"I can't thank the players enough for their support and wish them all a well-earned break."
Oxon started well in the wet conditions and led thanks to three penalties from Chinnor fly-half James Cathcart.
But on 35 minutes Johnson's yellow card for off-side gave North Midlands renewed impetus, which saw them score tries from fly-half Duncan Hughes and centre Mark Eastwood.
The sterling performance from the Oxon pack, led from the back row by skipper Andy Tibbetts (Newbury), continued into the second half.
But aside from a Martin Nutt (Newbury) try on 63 minutes, it was North Midlands who dominated the scoring.
Winger Jon Hal, lock Jon Taylor, hooker Richard Arnold and scrum-half Gareth Davies all added tries with a conversion apiece coming from James Lloyd-Jones and Ollie Thomas as the game finished 34-14.
Oxfordshire: (Chinnor unless stated): B Thompson (Nottingham), M Nutt (Newbury), J Hewitt, C Shaw (R Grimsdell), C Oyebade (L Gibson (Newbury), J Cathcart, M Thompson, S Matthews, P Fisher (Reading) (A Cawston), J Winpenny (S Chadbone (Oxford Harlequins), M Hutchins, A Smith (Newbury), A Milburn, T Johnson (Reading), A Tibbetts (Newbury, capt).
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