After much research and hunting in the internet jungle I have come upon a cunning plan.
I intend to install one of these,
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=120665030140&viewitem=&sspagename=STRK:MEWNX:IT#ht_9438wt_908
linked to the Bose Amp and speakers with one of these,which,incidentally ,Halfords wanted £110. for a harness adapter without the electronic wizardry yet only £40 to install the unit??
http://cgi.ebay.com/ebaymotors/ws/eBayI ... 1502wt_860
I'm also considering a reversing camera to link to the above unit and will definitely be installing an easily accessible connector ready for future upgrade.
I've ordered the parts and will update as to the progress,or failure,of the installation.
Wish me luck! Comrades !