SOLVED. Science fiction book with "knights" who can't take off armour once it's on. [s]

[Kiri]

I read this book 10-15 years ago. I took it out from the library and thought that the author's name would have been towards the end of the alphabet based on where I remember the book being on the shelves, but I was never able to find it again and can't remember the author or title.
I can't really remember what the cover looked like but part of me thinks it may have had a resemblence to Tad Williams' Otherland but this may just be as I kept seeing that book whilst looking for this one!
(view spoiler)[I believe it started with a mother and son on this world (?in Somerset or similar) who turned up at an out of the way house which for some reason had a portal in it - this bit is a bit fuzzy and I may be misremembering. But they end up in another world/reality where there are slaves who have collars round their necks, if they disobey these collars cause pain and if they try to run away kill them. Later on there is a "knight"-type character, always wears armour, face never seen, not very human in emotions etc, this knight dies and one of the companions has to take his place (I can't remember why), whereupon they discover that all the pieces of armour have blades that drive into the body of the wearer, including one in the helmet, these blades don't kill but seem to be partly responsible for the way the knights behave/relate to other characters. (hide spoiler)]

This book has been annoying me for years, every now and then it pops into my head and I would just like to know what it is!! I can't actually remember if it is a good book or not, I just know it frustrates me!
Thank you for any help.

[Kiri]

Bump

[Cheryl]

I'm glad you bumped this, as I hadn't seen your first post. I do think I know this, and I strongly suspect it's on my Mt. TBR. So, eventually I'll read it, and I'll come back here and post it. Of course, better yet, you bump it more often, and someone else knows it first! :)

[Feliks]

There's a scene like that in 'The Once and Future King'..

[Kiri]

Sorry, not either of those, but thanks!

[Feliks]

You're not thinking of Armor, are you? Not exactly knights; more like infantry. This book (+ Heinlein' 'Starship Troopers') was the basis for the movie of the same name.

[Wander]

It wouldn't be anything by Marion Zimmerman Bradley? End of the alphabet and she has books with knights, thought I'd throw it out there.

[Kiri]

Not Marion Zimmer Bradley from what I remember, different style, have read several of her books and not come across one like this.

[Kiri]

I do wonder if I have created this book in my head, but it is a very vivid fake memory if so!

[Ann aka Iftcan]

Ok, in the book Villains by Necessity there is a Black Knight traveling with the group who is unable to remove his armor until the very end of the book when he's hit with a powerful bolt of magic that peels the paint off of his suit.

[Lou]

I forgot that bit! I need to read that again.

[She]

bump

[Bryan457]

I 2nd
The OP hasn't been on since 11/2013.

[Ann aka Iftcan]

And they are not accepting any messages either. So I'm going to move this down to Possibly Solved and if the OP shows back up, she can move it back here if it's not Villains by Necessity

[Lobstergirl, au gratin]

Moving to Solved.