What? "in favor of a culture that resembled the British system he had sought to escape"?

The person in question (like many people under the umbrella of sentimentality) isn't necessarily being rational.

There isn't enough context to exactly give an answer but I'd guess he had to leave whatever country (the initial British system) for another country similiar is cultural stature because though he might have disagreed with how the British system worked, he couldn't see himself adjusting properly to moving to an alien or completely different social/cultural/political setting.

On one hand, he hates much of the culture of British society but on the other hand, he can't see himself living in any other setting that might be too exotic, too foreign to his tastes and lifestyle.

Did he have to leave one political setting because of legal trouble? What was the reason he left one country for another?

Here's a similar meaning:
She refused the diamond necklace even though she loved it in favor of one that had emeralds, although she hated the green stones.

Lawrence or Glubb Pasha?

The arab culture was one of the things which had attracted them to the area ( a separate, tribal system) but they were organising (for military reasons) the tribes into larger groups, which came to resemble the British system.
(or at any rate, the British military system)

(I disagree, for what it's worth, but that's what your text means)