Another split I made at the same time (was going to be a modified snelgrove too but after re-marking the queen the bees did her in so I just left the colony with 1 queen cell) has a newly laying queen.
PS: following the success of this second split (they are bringing me some honey as the colony is still large) It crossed my mind that just taking the queen away and reducing to one QC might be effective swarm control while maintaining a productive colony but Hivemaker has said in another thread that a large colony that has swarmed on a clipped queen might swarm again on the one virgin that remains after the one cell you leave has emerged. This, of course, renders the colony hopelessly queenless.
Comments anyone?