It'll probably be in the next series, just like the airport vehicle racing. Or it could go the way of the armoured cars thing and won't make it to air at all (the armoured car thing was seen, as I recall, in the previews for both Series 6 and 7). But I'm leaning toward it being held over for S14.
This isn't the first time TG has held stuff over, and it won't be the last.
Hope they don't bring the amoured car thing into Season 14. Everyone's gonna notice Richard's hair was much different back then.