A guest came downstairs this morning looking rather sheepish, and confessed that he had lost our loobrush head down the loo...

If you flush the loo now, the water comes right up to the brim before very, very slowly going back down. I rang a plumber, who said we would have to remove the entire loo in order to clear the blockage. Anyone know if this sounds right? I thought they'd be able to poke something down there to retrieve it.
Fortunately we have other loos, so it's not disastrous, just a pita. Any advice from plumbing-types appreciated!