“...in ancillary relief proceedings, while the court can admit such evidence, it has power to exclude it if unlawfully obtained, including power to exclude documents whose existence has only been established by unlawful means. In exercising that power, the court will be guided by what is ‘necessary for disposing fairly of the application for ancillary relief or for saving costs’, and will take into account the importance of the evidence, ‘the conduct of the parties’, and any other relevant factors, including the normal case management aspects. Ultimately, this requires the court to carry out a balancing exercise...”