  Second order ${\cal O}(\alpha_s^2)$ corrections to the heavy quark production
cross-section due to massless quarks and coloured scalars are calculated for
all energies above threshold. Based on the method introduced in this letter
also the gauge non-invariant second order corrections due to the pure gluonic
selfenergy insertion and a certain class of ${\cal{O}}(\alpha_s^3)$ and
${\cal{O}}(\alpha_s^4)$ corrections are determined. For the special choice of
the gauge parameter, $\xi=4$, the leading threshold and high energy behaviour
of the pure second order gluonic corrections to the cross-section are governed
by the gluonic self energy insertion.
