  We present results of timing observations of the 143-ms pulsar J0538+2817
that provide a proper motion measurement which clearly associates the pulsar
with the supernova remnant S147. We measure a proper motion of 67$_{-22}^{+48}$
mas yr$^{-1}$, implying a transverse velocity of $v= 385^{+260}_{-130}$ km
s$^{-1}$. We derive an age of the pulsar and S147 of only $30\pm4$ kyr which is
a factor of 20 times less than the pulsar's characteristic age of $\tau_c =
620$ kyr. This age implies an initial spin period of $P_0=139$ ms, close to the
present pulse period and a factor of several larger than what is usually
inferred for birth periods. Implications for recent X-ray detections of this
pulsar are discussed.
