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, hence the rarety of this P4. These are becoming harder to find today in "near mint" condition not seen 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 sheet. The bottom of the inner box is stamped Packer No 6 in red ink, circa (1980/1) 

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