You will need to slide the battery forward slightly in the direction that you removed the base clamp from as they slide in to a grove at the back and then it should lift out. Sometimes they will come out if you slacken the clamp right of as far as you can but normally it will need to come out and you need to squeeze your hand down there to get it out or trying getting in from one side.
I hope this helps but please feel free to ask if I can help you further
The battery is sliding forward and backwards freely but the clamp is on the right side. I've loosened the bolt but there is no room left or right to get the lip from the bottom of the battery out from under it? It's not possible to remove the clamp as it is bolted at the base and up further onto the body of the car. Even if I could remove this (I doubt with the space) I can't take it out from anywhere because of where it's situated?
Hi any chance you can send a picture of this clamp as normally you can get them out without too much of a problem?