On time, early or extra early?

Chiltern Railways generally have a pretty good reputation for trains rarely arriving at their final destination late.

One of the reasons for this is that they pad out their 'Public Timetables' like mad.

For example the weekday 1907 train from Bicester North to London Marylebone is currently due to arrive into London at 2027. That's 3 minutes later than usual because lots of brown things are currently falling off the trees causing train wheels and tracks to occasionally disagree with each other.

Officially though, according to the 'Working Timetable', the train is due into Marylebone at 2019. It cannot arrive much earlier because the platform into which the 2027 arrives is only vacated at 2014.

Tonight the train left Bicester 2 minutes early and was officially two or three minutes early at every stopping station or monitoring point along the route. The train arrived into London at 2017 (it couldn't arrive any earlier) some 10 minutes ahead of the public timetable and even 2 minutes ahead of the Working Timetable.

I can only think that the clock in the driver's cab must need adjusting - why would anyone deliberately leave so early as to potentially make many people miss the train?

Apologies for the dodgy formatting... If you don't believe me, the table below shows the comparison between the Public Timetable, the Working Timetable and the Realtime Record for the train I have decribed. A train showing a negative delay is early.

This isn't a theoretical exercise - I nearly missed the train because it was running so early.

Goodness only knows what will happen when the clocks go back this weekend!

Public WTT Working Realtime Location Arr Dep Arr Dep Arr Dep Dly Bicester North 1907 1907 1905 -2 Blackthorne pass 1910 No report Haddenham & Thame Parkway 1919 1919 1919 1919½ 1915 1917 -2 Princes Risborough 1926 1926 1926 1926½ 1923 1923 -3 Saunderton 1931 1931 1931 1931½ 1928 1929 -2 West Wycombe pass 1934 No report High Wycombe 1937 1938 1937 1938 1934 1935 -3 Beaconsfield 1944 1944 1943½ 1944 1941 1942 -2 Seer Green 1947 1947 1946½ 1947 1945 1945 -2 Gerrards Cross 1951 1952 1951 1952 1948 1949 -3 Denham Golf Club pass 1954 No report Denham 1956 1956 1955½ 1956 1953 1953 -3 West Ruislip pass 1959 pass 1956 -3 South Ruislip 2001 2001 2001 2001½ 1958 1959 -2 Northolt Park Jn pass 2002 No report Northolt Park pass 2003 No report Sudbury Hill Harrow pass 2004 No report Sudbury & Harrow Road pass 2005 No report Wembley Stadium 2008 2008 2007½ 2008 2004 2005 -3 Neasden South Jn pass 2010 pass 2007 -3 London Marylebone 2027 2019 2017 -2