Except David Lloyd George was able to act without hand tie because there was a strong public support. The fact was, after Passrachendaele British public realized the nature of Western Front and hence supported Lloyd George's "East First" strategy (I am not completely sure what was Churchill's role in this mess though) in order to avoid Haig sent their dear one to another high casualty operation. The result was Lloyd George simply arrested the necessary manpower replacement to BEF after Passrachendaele and went even further to cut down the size of it. Hence in spring 1918 many BEF units were understrength, contributed one major reason why German could pushed so much during Spring 1918 Offensive campaign.