Strike contingency plan Walthamstow to Heathrow
Depends if London Overground services are affected. Otherwise you
could go Leyton Midland Road (not far from the Baker's Arms) ---
Gospel Oak, across the platform and over the other side to the
Richmond platforms, Gospel Oak to Richmond, then bus 490 to Heathrow
He'd arrive far too late for a 7.40am check-in.