Why Britain would not buy an interned Graf Spee

Would the Royal Navy have bought an interned Graf Spee?

Probably not. Britain would value an inspection, but a single German raider would be difficult to supply, identify, and employ effectively.

The Royal Navy would probably inspect an interned Graf Spee thoroughly without trying to operate her. Technical access would reveal useful information about the raider's machinery, weapons, and sensors without creating an obligation to commission her. A lone ship would require non-standard 11-inch ammunition and support, while also risking confusion with German vessels wherever she deployed. A whole compatible fleet, such as French ships in 1940, is a different proposition from one isolated raider.