Let w be a semiclassical weight that is generic in Magnus's sense, and (pn)n=0∞ ({p-n})-{n = 0}^\infty the corresponding sequence of orthogonal polynomials. We express the Christoffel-Darboux kernel as a sum of products of Hankel integral operators. For ψ ∈ L (iâ.,?), let W(ψ) be the Wiener-Hopf operator with symbol ψ. We give sufficient conditions on ψ such that 1/det W(ψ) W(ψ) = det(I-Γ Γ ) where Γ and Γ are Hankel operators that are Hilbert-Schmidt. For certain, ψ Barnes's integral leads to an expansion of this determinant in terms of the generalised hypergeometric F. These results extend those of Basor and Chen [2], who obtained F likewise. We include examples where the Wiener-Hopf factors are found explicitly.