This is one interpretation of the Stormraven Stormbird that was at GamesDay 2009 well before GW released their version in 2011. It is much bigger than the new plastic model.
The Stormraven Stormbird Gunship is an armoured versatile craft that combines the role of dropship, armoured transport and strike craft.
That’s the Stormbird, not a Stormraven
http://www.tanksandtrolls.co.uk/40k%20Stormbird%20Troop%20Transport.htm