Mr Subramanian said the union felt the city had seen bigger cuts than most parts of the country and it was asking businesses and residents to join a "Stand-up for Birmingham" campaign.
Former Fulham and Birmingham striker Horsfield started the first match of the campaign against Rochdale, but was then limited to sporadic substitute appearances because of injury problems.
Stoke-on-Trent City Council, which is joint owner of the original hoard with the Birmingham Museum and Art Gallery, has said it will start a fundraising campaign to buy the new pieces.
In his first full campaign he took them to the First Division play-off final, where they lost on penalties to Birmingham, and after missing out on the top six last term, it has been wall-to-wall success this time around.