organic chemistry - Nucleophilic aromatic substitution on pyrimidines: C2 vs C4 selectivity

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The reaction of 2,4-halopyrimidines with nucleophiles generally leads to selective displacement of the halide at the 4-position:¹

In their textbook, Joule and Mills don't explain why, though, simply saying that it "is the normal situation for nucleophilic – 4-chloro > 2-chloro".

I don't see any obvious difference in the stability of the anionic intermediates, either (the so-called Meisenheimer complexes).

What can explain the regioselectivity of the above reaction?

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Reference

1. Joule, J. A.; Mills, K. Heterocyclic Chemistry, 5th ed.; Wiley: Chichester, U.K., 2010, p 257.