  The dynamical scaling of ageing ferromagnetic systems can be generalized to a
local scale invariance. This yields a prediction for the causal two-time
response function, which has been numerically confirmed in the Glauber-Ising
model quenched into the ordered phase. For a dynamical exponent z=2, a new
embedding of the Schr\"odinger group into the conformal group and the resulting
conditions for the validity of local scale invariance are discussed.
