The British tried their best to get Arabs to oppose ottoman Turkish rule. But Arabs are reluctant.
So the made a deal with the governor of Mecca. The grandfather to Jordan king. That if he can raise a army British will back him with a pan arab state. Stretching from present day Iraq to Egypt.
Needless to say, he could not raise a army unless British funded him plus support from British Army.
Upon victory and conquest of Damascus, British played him out. He was given Transjordan, his brother Iraq, but Mecca and arabian peninsular given to the Saud's. Syria and Lebanon to French. British maintain Palestine and Egypt.
The Europeans does not want a Pan arab state. They divided the post arab areas under ottoman into several mini states. To prevent the return of arab nationalism.