Canopy looks good to me - even with close-up photo.
I'd need to check my refs, if I can find them, but I thought that internal antenna was for the radio, replacing the mast.
The 40 inch 'Gee' whip antenna was normally mounted through the rear canopy, offset slightly to port, or where the original antenna mast was mounted, depending on Gee Mk and other equipment fit.
I have some notes somewhere, describing this, although they're not all that clear on exactly what's what.
However, from conversations I had with Mossie crews years ago, particularly Navigators, I was told that the original mast antenna was replaced by a whip antenna in the same location, and then eventually internally, and this seems to be confirmed by some photos showing the 'Gee' whip in the canopy, and a second whip at the mast location on the fuselage spine, with the later fitting showing only the 'Gee' whip in the canopy.
Some confusion can be caused by the 'Gee' whip not being visible in photos, due to the contrast in the print ( also sometimes deleted by the official Censor ), although if the inside of the rear canopy area is visible, the mounting tube can often be seen, when the antenna can't be seen.