The relationship between father Jiří Mucha and stepson John Omond continued to worsen in the 1960s.
John Omond renounced his Czechoslovak citizenship at the age of 16 and later also gave up his name. The same name he would again accept as his own, for purely economic reasons.
According to his mother Geraldine, John was continually having heated arguments with Jiří. John simply could not stand his stepfather, which is why he ended up leaving for England in 1966.
He gave up the name Mucha in England, changing his name to John Marcus Omond. Jiří Mucha issued a written statement dated September 14, 1972 declaring that John Omond is not his own son and that John’s real parents are film director Vladimír Čech and Jiří’s wife Geraldine. The fatherhood of John was well known by those closest to the Mucha family however after Jiří Mucha’s death, the fact became taboo under the threat of potential legal action by John Omond.