Sullivan was left frustrated by the collapse of Yeung's takeover (Getty)

The long-serving trio have spent close to �1.5m to take their combined holding to almost 50%.

Carson Yeung, whose takeover bid for the club failed in December, remains Blues' largest single shareholder with his 29.9% stake.

The news looks to have put paid to Yeung's plans to have Steve McManaman and Fan Zhiyi elected to the board.

Sullivan and the Golds were left angry when Yeung failed to deliver on his proposed takeover of the club late last year.

His intention to vote McManaman and former Crystal Palace player Zhiyi onto the board at an EGM was also met with resistance, with managing director Karen Brady writing to shareholders recommending they vote against the idea.

Yeung's representatives are still making positive noises over the future of the club though.

"With holding a 29.9% stake, we really hope to get more involved for the good of the club and the benefit of everybody," Yeung's spokesman Sammy Yu said.