Problem solved! Thought I would post to end the torment of others. I was being driven batty..
Apple Store provided the vital tip.
O2 UK (mobile phone service provider) said "it cannot be done"
RIM told the O2 store to advise me to buy "missing sync"...
The answer is :
In Leopard (OSX 10.5) Bluetooth sharing via the Apple Mac OSX firewall is by default OFF. In Tiger (OSX 10.4) it is ON by default.
This means that if you pair a BB via bluetooth with a mac running Leopard the Manage Connections ---> Bluetooth Options menu on your Blackberry will NOT show the option "transfer address book" (on my BB 8800 running OS 4.2) or "transfer contacts" (the equivalent option seen on my BB 9000 Bold) below the "device properties". If you try it with a mac running Tiger it will be there.
The solution is to, on your mac, go to System Preferences ---> Sharing ---> Bluetooth and check the box to switch Bluetooth sharing ON.
Delete and repair the BB and mac to be safe and you WILL now be able to transfer your ENTIRE Blackberry address book of contacts. It will download to the mac as "phonebook.vcf"
Import phonebook.vcf into Address Book on your mac.
Transfer the address book to your new BB if required using the free Pocketmac. I used a USB cable for this part.
The Apple Store stated it IS possible to transfer from a mac to a BB using Pocketmac via Bluetooth but I have yet to succeed in this, presumably via the "connections" tab in Pocketmac. If anyone has succeeded here do post.
As noted elsewhere, the Address book app itself in Leopard (as opposed to Tiger) no longer has a Bluetooth capability available. I shall not dwell on this point..