Quarry, by E.C. Tubb (epub/Kindle)

Radford threw a folder on the firing-bench. “All right,” he said before the agent could protest. “I know that you’re overdue for a vacation, but it can’t be helped. Things are on the boil. The discovery of the Free Union has shot the status quo all to hell and everyone’s out snatching for what they can grab. Both us and our friends of the Outworld Federation are eager to make friends and influence people—especially the people of the Free Union. We tell them that, as children of Earth, descendants of long-forgotten expeditions, they should come back to Momma and take their place in the Terran League. The opposition claim that, as long­term settlers on extra-terrestrial planets, their real interest lies in becoming a part of the Outworld Federation.”