The New Zealand Police Missing Persons - http://www.police.govt.nz/service/missing-persons/listing/quentin-thomas-godwin
Missing Persons NZ - http://www.missing.org.nz
Quentin has also been on the Australian Missing Persons database since 1994.
The Salvation Army carried out a search for him at our request - unsuccessfully. They are a helpful and resourceful organisation to contact: www2.salvationarmy.org.uk/familytracing
In the UK, there is the Missing Persons charity:
A joint site to help people searching for loved ones - www.look4them.org.uk/