The use of the Maestro invites you into a new way of carrying your instrument!
The thumb is held higher and is either straight or slightly bent. The result is a "natural and individual" posture. (Playing with the Maestro means that the thumb is opposite or only slightly lower than the index finger).
This thumb rest may require new holes drilled, please do not try this yourself as it may cause serious damage to the instrument, please let one of the Howarth Technicians advise you!!