Nice!
I wonder what the "AM Modifications" were? These were used during WWII as part of the effort to identify and locate the german 'Knickebein' navigation-beams, as well as trying to listen for radio-control signals being sent to early V2 rockets [the 'production' V2 didn't use radio-control and depended on inertial navigation].
I can understand the Air Ministry doing modifications if they were going to fly these in the like of Ansons. [The 1970s BBC series 'The Secret War' has a short clip of William Woolard(sp?) in an Anson with a S27]
The S27 I've got here has a "Pye" type coax-socket fitted to the rear panel and a screened-on front-panel identification that it's so modified.
"Modified for coaxial
?"
It's interesting too that round the 'Pye' coax socket on mine appear to be three small holes in a triangular layout - along with a hint of a circular 'shadow' on the chassis-plating, as if there was perhaps an earlier style of coax socket fitted before the Pye connector>??