First a practicality. Weekends of 11/5-6 and 11/12-13 the Picadilly line is closed between Heathrow and Acton Town. Replacement buses available. May be slightly slower. Assume you get checked into Hotel or store bags there and catch replacement bus about noon. At Acton Town take Picadilly to Leicester Sq. Go to TKTS booth and get a 1/2 price ticket for a play that night. Then walk south on Charing Cross Rd. maybe lunch at the Crypt of St. Martin's-in-the-Fields. Continue down Charing Cross and look at people in Trafalgar Sq. Continue south on Whitehall and sheck out the Hourse Guards, cross st and visit the Banqueting House. Continue down Whitehall, look down Downing Street and continue down to Parliament Sq. Maybe look inside Westminster Abbey. Back up to Big Ben turn right and head for river. Turn left up Embankment and got to Villers St. Turn left and hed up to the Strand. Cross over to the National Gallery and spend the rest of afternoon there. Closes at 6. Then head up Charin Cross to Cecil Ct. turn right and at next corner ia a good Indian restaurant. After dinner go to theatre and enjoy play. After play come back down Villers St. and cross the Hungerford Foot Bridge and come back on other side of bridge. Go to Embankment station and take tube to Acton Town and catch the bus back to Heathrow.