This is a superb example of the Wrenn W2230 BO-BO Diesel Locomotive in BR Blue, running number 8003 and BR motif.  Introduced by Wrenn, Basildon in Period 3,(circa 1972), production concluded in 1989, with just over 1000  produced the majority being issued in Period 3. These are becoming harder to find today in "near mint" condition and has not seen much layout use in my opinion. Most are "play worn", This example is not!

The Diesel comes in original box, with tissue, packing rings, Hornby Dublo coupling conversion kit, and single page instruction sheets. The bottom of the inner box has the familiar sellotape residue marks indicating P3 Basildon issue.(circa 1975). 

Overall Condition of the Diesel/box is "excellent to near mint", for its age.

NOTE : The simpler Motor/Trailing Bogie design of the Wrenn version compared to the Hornby Dublo version negates the layout  stuttering in many cases. This remains true for the Green variant as well.