Roof Light Cover Removal

[motorwaycafe]

Hello, I need to remove the inner cover of my Warwick Duo roof light (Behind the front seats).
.Not wishing to damage the plastic, can anyone please advise how it should be done?
Your help will be much appreciated.
(Photograph attached)
Regards and thanks
Motorwaycafe

 

[motorwaycafe]

I have just had advice from Auto Sleepers:
Service Centre- “I have spoken to the technician and he said you would need to remove it by force by prizing it away. He said it is secured on by nipples.”
It did take some force but came off in one piece.
Hope this helps others in a similar situation.
Merry Christmas to all.