  Quark line disconnected matrix elements of an operator, such as the axial
current, are difficult to compute on the lattice. The standard method uses a
stochastic estimator of the operator, which is generally very noisy. We discuss
and develop further our alternative approach using the Feynman-Hellmann theorem
which involves only evaluating two-point correlation functions. This is applied
to computing the contribution of the quark spin to the nucleon and in
particular for the strange quark. In this process we also pay particular
attention to the development of an SU(3) flavour breaking expansion for singlet
operators.
