Thanks for the replies folks,
The machine did start out life backed up - through a catalog of mishaps, delays plus increasing lack of sleep on my part, I ended up trashing the second backup.
Lesson(s) learnt this time is "don't use a huge disk that isn't easily replaced" for backups. Also don't use one of those poxy right-angled sata cables when the disks are real close together else you end up with the 3rd drive unconnected, write to sdc and end up trashing what should have been sdd. Most importantly don't yield to pressure to put an OS on the first backup disk in an attempt to recover the raid just because it has to be done before the shops open tomorrow.
Anyways, anybody got any thoughts on the FIFO problem (ie "p---------" from 'ls -l'). Virtually all the entries in lost+found have it set. I've googled for mkfifo() source but only gets links to how to use it rather than mkfifo.c itself. If I can see how it sets the bit likely I'll be able to clear it. Ideally it would be RHEL/Centos 5.5 but anything will do.