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The question often arises as to why the British Army did not use their 3.7-inch HAA guns in the primary anti-tank role as the Germans used their 8.8-cm FLAK. 3.7-inch was used its secondary anti-tank role on a few occasions but there are probably several reasons why it was not generally used in a primary anti-tank role:

The lowest level that 3.7-inch HAA guns were in the field army was usually in an AA Brigade controlled at Army or higher level. Typically a Corps might be allocated one these brigades, which usually had only one HAA regiment with 24 guns, and was used to defend assets in the corps rear area from air attack. The implication of this was that HAA deployment only rarely placed HAA guns where they might have a secondary anti-tank role and even if deployed in a primary anti-tank role might only provide about 4 guns (a troop) per brigade.
The role of HAA was critical in overseas theatres where ports, airfields and depots were liable to air attack. Furthermore this was not just an army matter, it affected the navy and the theatre's air force commander-in-chief also had a strong interest. Deciding where to deploy HAA was not solely an army matter.
The 3.7-inch HAA gun was larger and at about 9,500 kg almost twice the weight of the 8.8-cm FLAK. Its size and weight made it far from ideal for use in the forward areas. The large Matador tractor required for HAA guns was another disincentive to routine deployment in the forward area.
HAA guns were bigger and more complex than most guns and required more resources so increasing their production for anti-tank purposes during the 'crisis' period 1941-2 would have meant less of something else. Once 6-pdr became available the crisis passed and 17-pdr meant it never returned. Given a choice of 17-pdr or 3.7-inch HAA for anti-tank then only a complete idiot would opt for the latter.
After the war it was demonstrated that firing at the very low, close to zero, elevations needed for anti-tank shooting put stresses on the riveted mounting that led to it failing. It's unclear if this problem was known in 1941-2.
3.7-inch Mk 1 HAA guns did not have telescopes and for the first few years of the war there was neither AP shot nor open sights, although HE would have been effective, at least against anything before the Pz KfW Mk V (Panther). Nevertheless local expedient sights seem to have been developed.
From mid-1943 the anti-tank situation generally favoured the British and there was no need to mis-use HAA guns in this role and when the air threat decreased to the point where HAA was regularly used in the field artillery role there was no shortage of anti-tank guns either.

The general conclusion is that 3.7-inch HAA guns were seldom deployed in areas where they might have a secondary anti-tank role. Using them in a primary anti-tank role might have seemed a good idea to junior officers in the front line. However, the senior officers who actually commanded AA formations and usually 'owned' HAA units had a wider perspective of the war and most likely considered that the air threat was more significant. They were probably right.