After ending the year in the same way I started it (on a doubled up TPE 170), my total for the year is 8266 miles (Excel tells me I have done 8266.013 miles)
Although it didn't include the mileage for a couple of short hops of Metrolink and LUL, it includes the majority.
Checking back earlier, my total for 2011 was about 1500 miles less, so not too bad. I get a feeling mileage for 2013 will be lower, but we will see
My longest single journey of the year was on 390008, all the way from Glasgow Central to London Euston at 401 miles back in April (a day which saw a further Pendo journey of over 200 miles and a total for the day of 905 miles). April was also the month with the highest mileage at 3356, most certainly contributing a fair amount to my annual total