Wily, I checked on Archer. There's a book called The Master's Touch, Racing with Etienne de Mestre by Keith Paterson which has a full record of Archer.
He was even money favourite in his last race, the Champion Sweepstakes, but after finishing 3rd there was an uproar in the press that de Mestre had raced him when he was lame. He had had a swelling in a foreleg and a fever for a fortnight a while before the race. Archer was a heavy horse and hard to train. A spokesman for de Mestre said "Mr de Mestre runs his horses for his own amusement and ignores the right of the public to question any course he may choose to adopt".
He was taken back to Sydney to train for the Metropolitan in September but in August 1864 he was injured in training and retired to the stud at Exeter Farm where he stood until 1872. His breeders apparently preferred to keep his breeding secret as he had a short pedigree and so was not regarded as a thoroughbred according to Paterson.