AIUI, the Tranche 1 aircraft were meant to have the gun installed, but it wouldn't be supported (i.e. the aircraft would, in effect, be sans gun)
However, after a bit of behind-the-scenes work, it was then reported that the gun was reinstated as a capability, although this never seems to have been officially confirmed. Most sources seemed confident that this was the case.
However (again), it appears that Adam Ingram is of the opinion that the gun hasn't been restored (as a fully-working item) to the Typhoon, given one of his recent answers to parliament.
It would be interesting to learn whether or not the gun has been restored on the quiet simply as ballast; whether it has been restored on the quiet as a fully-working option; or whether it is, in fact, still the case that no gun will be installed on Tranche 2 and Tranche 3 aircraft (assuming that the latter are built).