Depending on your budget, if you want a slightly cheaper option you could look at Sunday/Sabbath bikes - they're cheaper than Enigma but v good quality. The September is their winter/audax bike.
http://www.sundaybicycles.co.uk/September.php
The company have changed their name to Sabbath since I got my bike, but it's the same bike as the one I have and I can reccommend it. It's light and responsive and the welds are very neat. I went to the workshop and test rode one for about 4 hours round the local hills before buying a frame/fork from them and I'm very happy with the bike. They can do the full bike, or bits; whichever you want. They will also polish the frame to the finish you want (ie, it comes in a matt, gunmetal type effect, or they can polish it to semi-sheen or full gloss) and you can choose the colour of the transfers (red, green, blue or black).
There is a review of their Silk Road (race type bike) here, it will give you an idea about the quality of the frame/fork though it is about the racing bike and not the audax one:
http://www.roadcyclinguk.com/news/article/mps/uan/2548