The Anglo-American bio-technology company is best known for its anti- venom serum for snakebites, particularly those of rattlesnakes and the North American viper.
At the same time as the company announced the board restructuring, it also said it was going to appoint a finance director to be based in London. The company, which is based in Tennessee but listed in the UK, plans to move its domicile to London ahead of a planned fund-raising exercise.
"The likely place to raise money is in London and UK institutions like to see British companies run by a Brit," Mr Wallis said.
He added: "I really enjoyed my time at Fisons and I had been thinking I would like to get involved in the pharmaceutical sector again." He said Therapeutic Antibodies had become aware that its board was too large, unwieldy and expensive. The seven directors to go included Professor John Landon, one of the company's founders.
Mr Wallis has enjoyed a terrific run of good fortune. He netted around pounds 1m from his stake in Scholl, the footcare company, when it was sold to Seton Healthier in May.
His stake in LLP, the Lloyd's List publisher, was worth around pounds 2m when the group floated this year. He has also made substantial sums from the sale of Sheffield Forgemasters, the engineering group, and from the takeover of Fisons in 1995.
Shares in Therapeutic Antibodies closed 2.5p up at 77.5p. They were 263.5p last autumn.