Stig,
According to this link:
https://books.google.com/books?id=U7...20%20E&f=false
the Hellenic Royal Air Force (HRAF) did use "E" to denote trainers. The photo does show a Avro Tutor E.50. One difference seems to be the period after the E.
The wing and struts visible in the photo do seem to match up with a Avro Tutor.
Here is a model of a post Oct 1940 Greek Avro Tutor. Here the period after the E seems to have been dropped.
In the comments on this model is a statement that 6 Avro 621s and 626s escaped to Crete where three were destroyed the remaining 3 made it to Egypt.
https://helaf.files.wordpress.com/20...04-model-2.jpg
Rolland