battery removal

[k9doc]

After being left for about a month (doh!) my battery has gone completely flat and jump starting doesn't give enough juice to crank the engine. After much trying, swearing, sweat and nearly tears I have given up trying to remove the battery which seems to be designed not to be removed. I ahve managed to remove both leads but there is just not quite enough space to remove the battery even on a tilt.
Is it possible without removing parts of the engine to do this??
Cheers.

[Extra 300 Driver]

It should be strsight forward, airbox off?

I commute between Southend and Stansted everyday, if you are near I dont mind lending another pair of eyes.