This gets a little bit brain-frying. I've looked at the multi-day continuous rides I have done:

8 600km Audax rides, with at least 200k done on two consecutive days

2 24-hr time trials, with at least 300k done on two consecutive days

The Mille Alba - 200 miles or more on 3 consecutive days

Paris Brest Paris x2. Each of these had 200km+ on 3 consecutive days. Technically with the 4pm start in 2011 I did over 200km on day 1, a further 400km to Brest on day 2, 400km to Villaine on day 3 and 200km to Paris on day 4

LEL - 200km+ on 4 days (the 5th day was a little under at about 180km)

Mille Miglia - 200km+ on 4 days - the first "day" was only 3 hours and we only did 120km on the last day.

If we use an Eddington number calculated on the basis of what was done on a Calendar day - this would give me an additional 22 rides of 200km (124.5 miles or more) - which would make a dramatic improvement to my Eddington number (imperial) from 102 to 118. Its much more difficult to work out what it would do to the metric number as several of the 400km rides I have done spanned 2 days and had between 136km and 200km on the second day. However, at the moment it would be fairly safe to say it was in the region of 161 due to the milestone-driven cluster of rides I've done of that distance or slightly over.

I guess, however, that Sir Arthur wasn't in the business of Audax or 24hr time trials and therefore did not have this conundrum. At midnight on a 24Hr time trial I wouldn't be able to tell you what road I was on let alone how far I had gone.

And, if we take Wowbagger's suggestion of a 24 hour period it gets even more difficult. At least it resolves the 24-TT situation but for the long Audax rides, especially the 600s I have no idea how far I would have gone at 6am on the second day as typically I would be halfway through the first stage after the sleep stop and wouldnt have a proper time of departure from the first go.

So, I'm going to stick with the way i've calculated it and know that on a strict definition the results are higher.

By the way - a 114 mile ride today has improved it per my calculation

but I guess would not under the strict defintion.