I would agree that it was the land based VLR aircraft that played a more significant role in closing the "Atlantic Gap", but would point out that not all Liberators in CC service were considered VLR due to their equipment & fuel tank fits.
On 31st May 1943 AOCin C CC issued instructions about the standard fits he was trying to achieve on Liberators in each squadron. He broke them down into various "classes". 15 Group was to have 3 squadrons (53, 59 & 120) "flown for range with a maximum depth charge load at the expense of anti-aircraft defence". 19 Group was to have 3 squadrons (86, 224 & 311) with aircraft "to carry sufficient armament to defend themselves against air attack and here range and depth charge load are of lesser importance". Due to their existing fits it was to take some time for squadrons to get an entire complement of aircraft for their designated roles (120 for example didn't begin to receive its Mk.V until Sept 1943).
So there were Class A, B (with 3 different sub-classes) & C Liberators Mk.III/V with different fuel tank fits and armaments plus a handful of surviving Liberator I in 120 squadron. While class A & B were to achieve a range of 2,300 miles, class C were to have a range of 1,600 miles. Class A were to be Mk.V while B & C were to be Mk.III or V. So 53, 59 & 120 were to become Class A equipped while 86, 224 & 311 were to get aircraft interchangeable between Class B & C. The GR.V with various types of centimetric radars didn't begin to reach the squadrons until Feb 1943.
A further reorganisation took place in Nov 1943 with another set of instructions issued about fuel & armament fits for each squadron.
53 squadron traded its Whitleys for Liberator GR.V in May 1943.
59 finally became Liberator GR.V equipped in March / April 1943
120 had had Liberators since 1941
86 had begun to receive Liberator III in Sept 1942
224 converted to Liberator III between July & Sept 1942
311 converted to Liberator GR.V betweeen June & Aug 1943.
Often forgotten are the 2 Fortress squadrons, 206 & 220, that had been the mainstay of the CC long range effort from Sept 1942 to March 1943 when Liberators became more numerous. The Fortress IIA/II had a range of around 1,825 miles. They were moved from the Western Isles to the Azores in late 1943 after an airfield was opened at Lagens.