Welcome to the forums.
I can certainly understand why you are keen to source a bottle of your namesake whisky. Charles MacLean has written a usefull little book, called "Scotch Whisky", in that volume (published 1993), I found the following bit:
Charles Maclean wrote:McCallum’s Perfection
The brothers Duncan and John McCallum went into business together in Edinburgh as innkeepers and wine and spirits merchants in 1807. Their base of operations happened to be a pub known as the Tattie Pit*, which was soon expanded to include a shop and warehouse. By 1914, the McCallums numbered many members of the Scottish aristocracy among their customers.
Sadly, the pub was utterly demolished in April 1916, during the only zeppelin bombing raid of the First World War, that took Edinburgh as its target.
Long before this date, however, the company had passed to the brother’s nephew (they had remained bachelors). Duncan McCallum Stewart, who set about selling his brands overseas rather than in the home market.
McCallum’s Perfection was introduced in 1911, and became a favourite in Australia (where the company established an office in Sydney) as well as in New Zealand. It is one of only two brands described as ‘Scots’ whisky (the other is Cutty Sark).
McCallum joined DCL in 1937 Perfections is available in the UK, but its principal market is in Thailand. Secondary markets are in New Zealand, St Kitts and Nevis.
Time was when every misty glen,
From Cruachan to Cowal Shore,
Saw clans that gathered for the fray,
Their gathering cry ‘McCallum mhor’
These days are dead and gone now,
But in Auckland, Sydney or Quebec,
Where Scots forgather day by day,
Their gathering Cry is ‘More McCallum’.
* Kid you not
The SWA brand site Kildalton found above, suggests you should contact Diageo for information on UK resellers:
8 Henrietta Place
Tel: 020 7927 5200
Fax: 020 7927 4600
Hope this helps