How successful was Anglo-German diplomacy in the 1920s? (Modern World History, OCR exam board, A-level question)

At the end of the 1920s there seemed to have been a positive step forward in peaceful relations between Germany and Britain after the antagonistic peace brought about by the Versailles peace treaty. The Locarno "honeymoon" had created a feeling of goodwill among the general population at least in Britain. Yet behind the closed doors of the negotiating table leaders/diplomats must have been aware of the limitations of the existing peace and friendly 'spirit'. …

…of cooperation may have held long enough for German grievances against Versailles to have been appeased completely even with French fears and Fascism in Germany avoided. The Economic depression following Wall Street highlighted the failures of the 20's: British and German diplomats (among others) had failed to heal the scars of Versailles. France was still fearful, Germany still vengeful and America still unfaithful to the idea of collective security it had helped to create in 1919.