The juvenile male, which measures to approximately 4.5 metres long, was found stranded in The Wash between Norfolk and Lincolnshire.
The Catacean Strandings Investigation Programme (CSIP) at the Zoological Society of London (ZSL) are investigating the circumstances of the animal's death.
They said, despite the apparent decomposed condition, it is likely he died weeks ago.
ZSL's Rob Deaville and Matt Perkins collected a range of samples from the animal where they will analyse bacteria, tissue, and possible pollutants.
Tests will also include dietary studies, life history, age and population genetic analysis (ZSL).
They explained there was no evidence on recent feeding as its stomachs were largely empty, however they did find a large fragment of plastic in the whale's first stomach.
They stressed it is important to note, while it is not good to find the material there, it did not kill the animal as no gastric impaction was caused.
As this is a rare case, it is believed the analysis will inform UK marine mammal research for years to come.