  We use the known renormalon structure of Bjorken polarised sum rule (BSR)
${\overline \Gamma}_1^{p-n}(Q^2)$ to evaluate the leading-twist part of that
quantity. In addition, we include $D=2$ and $D=4$ Operator Product Expansion
(OPE) terms and fit this expression to available experimental data for
inelastic BSR. Since we use perturbative QCD (pQCD) coupling, which fails at
low squared spacelike momenta $Q^2 \lesssim 1 \ {\rm GeV}^2$ due to Landau
singularities, the fit is performed for $Q^2 \geq Q^2_{\rm min}$ where
$Q^2_{\rm min} \approx (1.7 \pm 0.3) \ {\rm GeV}^2$. Due to large BSR
experimental uncertainties, the extracted value of the pQCD coupling has very
large uncertainties, especially when $Q^2_{\rm min}$ is varied. However, when
we fix the pQCD coupling to the known world average values, the $D=2$ and $D=4$
residue parameters can be determined within large but reasonable uncertainties.
