Championship sides Bristol, Yorkshire Carnegie and Doncaster have all met the minimum criteria to be accepted into the Premiership next season.
The trio's grounds have met the minimum standard required ahead of the league's play-offs, which start this weekend.
Should Doncaster go up they would play matches at Doncaster Rovers' Keepmoat Stadium, rather than Castle Park.
Bedford did not apply to have their ground audited and would not be promoted if they won the play-offs.
London Irish will finish bottom of the Premiership if they fail to beat Harlequins on Sunday or Newcastle win at leaders Saracens.
But the Reading-based side would stay up if Bedford win the play-offs.
The Blues finished fourth in the Championship's regular season, 31 points behind leaders Bristol who they face over two legs, with Yorkshire Carnegie and Doncaster meeting in the other play-off tie.
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