A 1997 paper by Major G.C.Clark offers a provocative challenge to the general historical acceptance.
Some of the myths he's arguing against seem to be largely his own creation. He also makes fundamental errors in his attempt to deflate those myths, too.
From the paper:
The CH system was the only English radar system in operation at the outbreak of the
war.
The British failed to develop gun laying radar such
as Würzburg, for flak batteries and Seetakt for naval guns, in the pre-war years.
Production of the GL Mk1 radar started in 1938. It was operational by the end of the year, the first units sent overseas in March 1939.
AMES type 9T went operational right at the start of the war.
AI Mk1 was in operation early in 1939. AI Mk II went in to production in August 1939.
Costal Defence MK II radar went in to production in June 1939.
The RN's Type 79 air search radar went operational in August 1938.
The improved Type 279, a combined air warning/gun laying radar, entered production in early 1939.