What does CHERUB stand for?

If you have read the book Secret Army (which is a book from Henderson's Boys), you would know that Charles Henderson decided to make an espionage unit. At the end, he explained what CHERUB stood for.

The C was for Charles

The H for Henderson

The E for Espionage

The R for Research

The U for Unit

And the B was for B

Charles Henderson's Espionage Research Unit B.