Not a rose expert here, however I'll give it a try.

Climbing roses clinging on the outside and running through.

Roses filling under the hedge where the hedge can't or does not grow.

I think Holly would be better, but A massive cane of climbing rose
can be strong and nasty to work with.

Thorns - try Forth of July - thorny. Streaked red and white.

Martin

Peterllewellyn wrote:
Hi I am new to gardening so forgive the silly questions - Is there a
Rose bush that can be planted within a grown hedge to help with
security (thorns) thanks peter