Wilf,
it was hardly Liddell-Hart's fault that the British Army was too dumb to issue 40mm HE shells for the 2pounder, even for infantry support tanks as the Mathilda II. Meanwhile French and Germans issued even 37mm HE shells.
The few "close support" CS versions of British tanks which carried a 76mm low velocity gun didn't compensate for this usually overlooked and disastrous hit on British tank firepower in 1939-1941.

Liddell-Hart did neither dictate that a tank needs to have a length:width ratio that made pivoting difficult and allowed only for small turret rings which didn't enable the use of recoiling long 76mm guns.

He wasn't responsible for the timetable which turned the Crusader into a tank which - despite hasty design and subsequent teething problems - didn't absorb lessons from France in time for the Desert War.

L-H didn't request the Covenanter to have a freakishly high ground pressure either, did he?

It wasn't his fault that the 2pdr AT gun was too complex and not superseded in time by a better gun, or for the fact that the British equivalent of the 8-8 was too heavy for tactical deployment in land battles for AT purposes.

L-H wasn't at fault for metallurgical problems in AP shell production which led to many AP shells breaking up on German face-hardened armour, either.

The division into infantry and cruiser tanks wasn't a major mistake either, as proved by the StuG III later on. Guderian was actually wrong on this one early on.


So how exactly did L-H mess up British tank development?

The British tank development mess of 1930s till 1943 looks to me rather like an engineering and procurement bureaucracy failure.