Dear all
Thanks so much for all your replies - they have really, really helped me to see things more clearly. Needful as we were woken up soon after 5 am by a panic stricken DS who'd been up all night.
At first, encouraged by some of your posts, I strongly encouraged him to submit, along with the special circs form for mitigation. He beavered away but it wasn't going to happen. DH rang his department, didn't mention DS' name, and was told that he should get his dissertation in as soon as possible and the spec circs form at the same time. And that DS should see them asap. So, shortly before the deadline, he dropped tools and saw his department. Upshot is that he submits on Monday - at the start of his exam season - but that's what they said. And along with the spec circs form and GP letter. A panel will consider things so of course DS is very worried but he left himself with no option. He didn't think he should push his luck by asking for even more time.
Now may not be the time to remind DS that his proposal was accepted some months ago and that despite a heavy essay load, he could have made much more headway. His diss supervisor has only just come on the scene, however, and while the teaching is good at his uni, the level of tutor support seems oddly very poor. DS has never met his personal tutor - well once, at the start of his three years, when the tutor, apparently, told his tutees that it was unlikely they'd ever need to see him and that they certainly wouldn't see him about anything pastoral. How much of that is DS's interpretation, I don't know, but the hands off approach does seem at odds with the generally very good reputation of his department.
So, the diss won't be as good as it could be and completing it will interfere with exam revision but DS may have had a lucky escape. I've found today exhausting - back to work tomorrow and then maybe helping DS proofread - if he's even at that stage by the weekend.
LORD - you are so right - each and every institution will have its own procedures. In DS's uni, it appears that departments themselves have their own systems.
Thanks again. What you all said about DS' procrastination, notwithstanding the Easter illness, is spot on. But I think he's learnt a lesson without my saying very much at all.