Here are some excerpts in support:

Excerpts from pages 5-6:

The political event in the early 1920s of most relevance to the subject of this book was the worsening of diplomatic relations with France in 1922. In the course of discussions on the 'Continental Air Menace', Lord Balfour commented:

Day after day, night after night, the capital of the Empire would be subject to an unremitting bombardment of a kind which no city effectively acting as the military, naval and administrative centre of a country engaged in a life and death struggle, has ever had to endure."

Concern over the size of the French Air Force led to the decision to strengthen the RAF, for it had been much reduced in size after the end of the 1914-1918 war. There followed two Home Defence Expansion Schemes. That of 1922 for 23 squadrons was soon superseded by the better known 1923 scheme for 52 squadrons...

The Salisbury Committee's term of reference were to enquire into the cooperation and correlation between the Army, Navy and Air Force, and inter alia, into 'the standard to be aimed at for defining the strength of the Air Force for purposes of home and imperial defense'. The Committee issued an interim report in June 1923 which included the recommendation that

British air must include Home Defence Air Force of sufficient strength adequately to protect us against air attack by the strongest air force within striking distance of this country.

The Cabinet endorsed the Salisbury Committee's recommendations... the Air Staff later argued that it was based upon a assessment of the threat. They explained to the Committee of Imperial Defence that 'The object is to attain, and maintain, approximate numerical equality with the French Independent Striking Force'. The justification for this was that

At the present time France is the only power which maintains a powerful air force within striking distance of Great Britain.

The Estimated potentiality of the French air force, therefore, is used as a basis for calculating the air defense measures necessary for this country.

We will see that this consideration shaped the Air Staff's views on operational requirements, and on airfield location, long after any thought that war with France was conceivable, because some basis for defence planning was required...

Excerpt from page 8:

The emergence of Germany as a military threat in 1933-34 led to a major realignment of Air Staff planning in many respects. Before 1934 the RAF's operational squadrons had been disposed to counter an air attack from France, but in August 1934 the Air ministry was instructed to prepare plans from the air defence of Great Britain for war with Germany. These were to assume that France was an ally, and include the possibility that German aircraft would overfly Holland and Belgium, or occupy airfields in those countries. Germany as the potential enemy meant that attacks were now to be expected from the east rather from the south, with consequent reorientation of the RAF's fighter defence system. Needless to say, a direct effect of considering Germany rather than France as the potential enemy was greatly to increase the operation range required of bombers, and in consequence their size.

Excerpt from page 16:

Most bomber squadrons were to be stationed in Oxfordshire and Gloucestershire, where they would be protected by the Aircraft Fighting Zone... For many years the radius of action specified for most bomber types was no more than sufficient to reach Paris and the industrial regions of North-East France from those bases. When Germany replaced France as the potential enemy the best location for RAF bomber squadrons would be in East Anglia and Yorkshire.

So in the 1920s, Britain used France as its nemesis for war planning and it wasn't until 1934 did the planning focus switch to Germany. Now, I wonder if Britain had prepared for war with Germany in the 1920s would appeasement would have been a necessary delay tactic?