Once again, thanks for the replies chaps. However looks that I,m no further foward as is does seem that it's not possible to identify a current agency / radio frequency from a squawk code. Incidently for those in the, "they keep the same squawk code camp", just this morning the KLM 16X (MME - AMS) Transmitted three different codes before it had reached the Ottringham VOR a distance of about 80 miles and this is the norm.