  We study the spatial homogenisation of parabolic linear stochastic PDEs
exhibiting a two-scale structure both at the level of the linear operator and
at the level of the Gaussian driving noise. We show that in some cases, in
particular when the forcing is given by space-time white noise, it may happen
that the homogenised SPDE is not what one would expect from existing results
for PDEs with more regular forcing terms.
