Nameless Irish shared The Stoop before moving into the Madejski.
They were they for only one season 1999/2000, averaging just over 4000.
https://en.wikipedia.org/wiki/1999%E2%8 ... ugby_union)
I suspect that if they go down, crowds will be even lower than that at the Madejski, and at £25000 a game, the first 1000-1500 of that will go straight towards paying rent.
The Madejski is a horrible venue when crowds get to that level, which will put fans off going.
In short, London Irish could be stuck between playing in a venue that's far too big and too expensive, and simply having nowhere else to play.