Metrobus 323 ex M804 (KYV804X) is taking at break at Union Station.
The former Seville Metrobus, 325 - though 324, ex London M224 joined it - is seen alongside the grounds in front of the White House, which is behind it.
Former London M219 (BYX219V), now numbered 321, is waiting outside Union Station for its next tour. The bus arrived in Washington in 2009 having spent 8 years on Stratford on Avon tours.
...and here is M219 as 219V in Stratford on Avon in summer 2004.