  We give a complete treatment of factorisation of Deeply Virtual Compton
Scattering (DVCS) in the generalised Bjorken limit, using the local Operator
Product Expansion (OPE). The method allows a straightforward proof that, at
leading twist, the DVCS amplitude factorises into an integral over coefficient
functions and Skewed Parton Distribution Functions (SPDFs). The integral is
well defined for on-shell final state photon if the Wilson coefficients satisfy
a certain factorisation condition, which we derive. We also show that it
enables a simple proof that soft singularities either cancel out or, in the
case where the final state photon is on shell, are integrable. This confirms
the argument of Collins and Freund. Further, we repeat the tree-level
calculation of twist-three contributions to DVCS off a scalar target, where
factorisation was found to be violated. We propose a new definition of the
structure functions and calculate the coefficient functions, which are such
that factorisation works.
