After a trip to Toolstation for a long handled screwdriver I could remove the hard drive cage and fan. However the cage was too large to slide out the side of the case, so next up was removing the top shelf that supports the hard drive cage and optical drive.
The shelf was held in neatly, however it also contained the lock for the side panel which tricky to remove and felt quite flimsy. Care had to be taken not to snap it. Once this was out the shelf rotated out and out came the hard drive cage.
All that was left to remove were the cables that were clipped down diagonally across the back of the case which were held in place with double sided tape.