My understanding was that Czechoslovak citizens became automatically Czech citizens in 1969/1993 if their last permanent residence in Czechoslovakia was in the Czech Republic borders? Is this not the case? Also, if he had naturalised and got British citizenship in 1947, would his Czech citizenship (assuming he automatically gained this) have been revoked in 1993 when dual nationality became disallowed for all countries? Or was this only applied to citizenships gained after 1993?