from the proverb "After the Lord Mayor's show comes the dust-cart" (or "donkey-cart", or "shit-cart"). Bringing up the rear of the Lord Mayor's Show is a team to clean the manure of the pageant's horses.
The All Whites came into this match hotfoot from their stunning victory over Castres last Tuesday which took them into the semi-final of the prototype European Cup. ... For a while it looked as if it might be a case of after the Lord Mayor's show as Swansea struggled with one of their dozy moods, against Treorchy.
2006, Jeremy Carrad, Running on Empty, (Pegasus Elliot Mackenzie, ISBN 1843862182), p. 40: