[1][2] In June 1911 he fought Billy Papke for the British version of the World middleweight title, losing after being knocked down at the end of the ninth round and failing to come out of his corner for the tenth.

[7] On 12 April 1912, after suffering ill-health for some time, Sullivan relinquished his British title and announced his retirement from boxing, intending to undertake a sea voyage to regain his health.

He travelled to Australia in 1913 where he beat Reggie Midwood in April and there were plans for a fight with Australian champion Dave Smith but Sullivan suffered a poisoned foot and was beaten in Sydney by Bradley in July and in October by Jerry Jerome.

[13] Sullivan served in the British Army during World War I and by 1916 had reached the rank of corporal in the London Scottish.

[17] By 1919 he was a Director of Physical Training in the Army and featured in newspaper adverts endorsing Reudel Bath Saltrates.