interior light fittings

mickrumble

Hello all, I have a 2006 Ace Award TriStar and I suspect that a bulb in one of the circular light fittings on the ceiling has failed. I cannot see any obvious way of gaining access to the bulb. I am sure there must be some way of easily removing the translucent
centre of the light fitting to access the bulb but I cannot see it!

Help please!