Application of Small Companies Corporation Tax Rate

A client is about to invest in a business and for the purpose will invest via a new company which will acquire the shares of Oldco.
Newco is unlikely to trade but may have some management charges to cover incidental costs within itself.
Will Newco be regarded as carrying on a trade and thus would the Smaller Companies Rate threshold be reduced to £150,000 for both Companies?
If so, would it be preferable to create Management Charges Income into Newco to spread the effects of the shared thresholds?
Jon Morley