Financial constraints had made it impossible to produce a vehicle suitable for close support and for exploitation.

Martel considered that medium tanks were too complicated and expensive for infantry support, where they would be too vulnerable to anti-tank weapons and rejected claims that they could fire accurately when moving, so would gain no benefit from their speed.

Tanks were necessary for mobile operations in armoured divisions and for infantry support in attacks on fortified defensive positions; a vehicle satisfactory for both tasks appeared to be impossible to attain.

When gaps had been forced through the opponent's front by the infantry tanks, cruisers were to penetrate to the rear and attack lines of supply and communication centres in accordance with the theories of J.F.C.

[clarification needed] An even bigger problem for most cruiser tanks was the small calibre of their main gun.

This gun had adequate armour penetration against early war tanks but was never issued high explosive ammunition.

This made the cruisers less able to deal with towed anti-tank guns, which was a serious deficiency at the long ranges of engagements during the Desert Campaign.

As the armour of German tanks increased British cruisers were up-gunned with the more powerful 57 mm Ordnance QF 6 pounder, starting with the Crusader Mk.

As the Cromwell could not be fitted with the HV 75 mm, work was undertaken to produce a tank for the powerful 17-pounder anti-tank gun, able to take on the most powerfully-armed German vehicles.

The Cruiser Mk VIII Challenger was developed, mounting a 17-pounder gun on a lengthened Cromwell hull in a new turret.

The cut in armour protection to allow the mounting of the larger gun meant it was not well suited to closer range engagements and it threw its tracks more often than the Cromwell.

The Comet was a further development of the Cromwell, a "heavy" cruiser tank, which sought to remove the need for 17-pounder armoured vehicles, such as the Challenger or Firefly.

Despite the emphasis on mobility, most early cruiser designs were plagued by mechanical unreliability, notably in the hot and gritty desert of the North Africa Campaign.

[2] In 1934, Sir John Carden of Vickers-Armstrongs had produced a "Woolworth" medium tank to a 1934 specification (General Staff number A.9) for a close support tank, using elements of the Medium Mk III design (which had been abandoned due to financial reasons) but lighter and using a commercial engine to be cheaper.

It was insufficiently armoured for the role but as a "heavy cruiser", it was put into production in July 1938 as another interim design.

[5][6] The tank A13 E1 was rudimentary and too small for British use but the Nuffield suspension was most effective and this became the basis of the Cruiser Mk III (A13).

[8] The Tank, Cruiser, Mk VI, (Crusader), was used in large numbers in the Western Desert Campaign.

Centaur and Cromwell tanks were an alternative design using the Cavalier engine and the new Rolls-Royce Meteor respectively - the three vehicles were similar in appearance.

During the war, the development of much more powerful engines and better suspension enabled cruiser tanks to increase in size, armour and firepower while retaining their speed and mobility.