Sadly I used to have a whole pattern book but I have it away as I thought it was something I would never need.

As I said in my original post, Google hadn't been much help, hence why I came here.

There are lots of patterns for table runners that can be made as bed
runners. Either make more blocks for add more borders. I guess
you have to determine the size that you want and go from there.
Check American Patchwork and Quilting. They have lots of patterns
for table runners that would also work as bed runners. Or use a
quilt pattern and make it skinnier. Graph paper or spreadsheet
is your friend when you want to resize a pattern.

great article on bed runners for hospice patients
 

https://www.allpeoplequilt.com/magaz...ed-bed-runners

This article has colored photo of lovely bed runners to inspire you for your project. I hope it helps.

So I found the book Sampler Spree by Susan Ache. This sounds like a book where you can make your blocks and put them together how you wish. I'm wondering if this might be fun to make the bed runner from!

Why not? A bed runner is just a big table runner or a small/longish quilt.
BTW, I just saw a new book by Doug Leko 'Tabletastic 2 Quilt Book'.
Not affiliated. Just saw it on the Fat Quarter Shop website.
Have fun and show us what you make.

Sewingpup, great idea!

EasyPeezy, interesting article. What a wonderful way to share our love of quilting.

beckyboo1, the book looks like a great way to dive in. Share your results with pictures!