Historically speaking, the British have been diplomatic fools in the middle east -- setting up evil with short-term gains. Right from the early 1800s when they propped up the Ottoman Turks instead of freeing Christians, to when they put Sunnis and Shias in a Christian Lebanon, to when in WWI they didn't attack at Antioch, when there was clear news of Arabs (under the Hashemites and secular pan-Arabism) and Armenians and Kurds ready to overthrow the Turks; instead they expended blood and thousands of lives at Gallipolli.
No, the Brits are an expended force -- let the Middle Easterners come under Russia and China and India's thumbs.
The Russians and Chinese won't be so nice -- look at Russia's brutal yet effective, people moving in the 1940s and 50s -- creating ethnically pure states.
They will slaughter all the non-Christians out of Lebanon, create Alawite and Christian Syrias, Christian Assyria, probably also a wider Armenia
Plus, the Russians will be kept busy for decades in the Middle East and Turkey -- no time or ability to cause mischief in the west.
In engineering the current M.E. Britain had a distinct agenda to serve the British Empire that was. Today that British Empire does not exist, and geopolitics have significantly changed too.
Of course, Britain still has her political, but more so her economic interests in the M.E. as much as the Russians, Americans, and the Chinese, in that region.
What I was saying before here was in a context & specifically about helping the US by using British diplomacy and influence to transition the House of Saud out of being custodians of Mecca and Medina, whilst limiting their ‘other support’ for the Saudis and the Gulf states.
The ‘other support’ includes: selling military equipment to them (along with the U.S.), doing business deals with them, and quit publicizing how ‘liberal’ & religiously tolerant the Gulf states are because they got nightclubs, a surplus of British tourists, and build a church or two to show goodwill.
Surprisingly or not, Russia exercises a great deal of diplomacy (not brutality) with Iran, as does China (to a lesser extent), to rein in the Mullahs in Iran.
With the Saudis, the Russians are definitely much less tolerant.
Needless to say, both the Saudis and Iranian regimes know exactly where they stand with Britain, USA, Russia and I should think with China too.