Just checked my stash, and none Steve. Like i said try a 3amp fast blow, may hold until you can get a 2.5 SB.

Whilst digging around I found these fuses, they are pretty old, and are solid white inside. Any chance these are slow blo?

Slow Blow fuses usually have the markings on one of the ends indicating they are either "timed" or "slow blow".

A "timed" 2.5A is: T2.5A.
While a 2.5A Slow Blow can be a few different markings, but usually MDL2.5A.

Either way, Slow Blow or Timed have one of 3 fuse wire types: A white string with a spring wrapped all around it, a wire with 2 bubbles on it, or a spring that goes half way then a wire for the rest.

Those solid white fuses make it really hard to tell what they are exactly, and if they have blown.