Thanks for the comments everyone.
I've now dried these by putting them in a very, very cool oven (60 deg C) for 8 hours; they've shrivelled impressively, and smelled gorgeous while drying out.
As regards differentiation from gyromitra esculenta, the following is from the Wikipedia entry on morels:
"The key differentiating features of false morels in comparison to morels include:[27]
* The false morels can be told apart from the true morels by careful study of the cap, which is often "wrinkled" or "brainy", rather than honeycomb or net-like. Gyromitra esculenta has a cap that is generally darker and larger than the true morels (Morchella sp.).
* The caps of early morels (Verpa sp.) are attached only at the apex (top) of the cap, unlike true morels which have caps that are attached at or near the bottom. The easiest way to tell the false from the true variety, is to simply look inside the stem.
* False morels contain a cotton-ball looking substance inside their stem while true morels are hollow inside.
* The caps of the false morel can be easily twisted in comparison to the normal morel.
* False morels are often a brown, reddish color."
The hollow central stem certainly seems to indicate that these are morels, but I'd still like an expert to give a definitive verdict. I'll have to Startpage for specialist fora (flora fora!).
