There are two ends to the 4DD currently in preservation.

There are DEMUs on here, they are not EMUs , also a 508 is not a 4- PEP these were class 445

4PEP = 4 car PROTOTYPE Electro-Pneumatic. There were two x 4-car and 1 x2 car prototype units which entered service for a short trail period around 1972-3. The "PEP" unit in the picture is actually a production Class 508, all of which later migrated to Liverpool, to be replaced by the even worse class 455 units, with their dangerous 3-step brake that HMRI were distinctly unhappy about, and these heaps of junk are still in daily use. Not that anything that has been built since is much better......