We (users of the train service) have always felt that the service is less reliable than many other train services, but we've been assured by Wessex trains that we only suffer delays and cancellations in the same proportions as other lines.  This one is very difficult to prove either way, and isn't helped by looking at what is defined as a delay, and what is a cancellation.

In the week from last Monday to last Friday, 1 train was cancelled (my definition) and 2 others experienced severe problems - either they were very late indeed, not having left Westbury / Swindon by the time they were due at Melksham, or they broke down or stopped short before they got here, or the reporting system failed and you would have been left hanging around not knowing what was happening.   Here's my log in detail.

22:37 train on 20/01/2006 was on time
21:33 train on 20/01/2006 left at 21:35
18:09 train on 20/01/2006 left at 18:11
17:02 train on 20/01/2006 was on time
14:49 train on 20/01/2006 left at 14:50
13:35 train on 20/01/2006 was on time
09:12 train on 20/01/2006 left at 09:13
07:45 train on 20/01/2006 left at 07:49
06:56 train on 20/01/2006 was on time
05:52 train on 20/01/2006 was on time
22:37 train on 19/01/2006 was on time
21:33 train on 19/01/2006 left at 21:35
18:09 train on 19/01/2006 was on time
17:02 train on 19/01/2006 was on time
14:49 train on 19/01/2006 shows as No report
13:35 train on 19/01/2006 left at 13:37
09:12 train on 19/01/2006 shows as Cancelled
07:45 train on 19/01/2006 was on time
06:56 train on 19/01/2006 was on time
05:52 train on 19/01/2006 was on time
22:37 train on 18/01/2006 shows as No report*
21:33 train on 18/01/2006 left at 21:35
18:09 train on 18/01/2006 was on time
17:02 train on 18/01/2006 was on time
14:49 train on 18/01/2006 was on time
13:35 train on 18/01/2006 left at 13:37
09:12 train on 18/01/2006 left at 09:13
07:45 train on 18/01/2006 left at 07:47
06:56 train on 18/01/2006 was on time
05:52 train on 18/01/2006 was on time
22:37 train on 17/01/2006 was on time
21:33 train on 17/01/2006 left at 21:35
18:09 train on 17/01/2006 was on time
17:02 train on 17/01/2006 was on time
14:49 train on 17/01/2006 was on time
13:35 train on 17/01/2006 left at 13:37
09:12 train on 17/01/2006 was on time
07:45 train on 17/01/2006 was on time
06:56 train on 17/01/2006 left at 06:57
05:52 train on 17/01/2006 was on time
22:37 train on 16/01/2006 was on time
21:33 train on 16/01/2006 left at 21:35
18:09 train on 16/01/2006 left at 18:11
17:02 train on 16/01/2006 was on time
14:49 train on 16/01/2006 was on time
13:35 train on 16/01/2006 was on time
09:12 train on 16/01/2006 left at 09:13
No log details for the 05:52, 06:56 and 07:45 that morning as I was testing my program. I was around and about and they did run as I recall, on or nearly on time.

My meaning of "cancelled" is that a train fails to provide a service arriving in or departing from Melksham at (or within the following 2 hours) of when it is timetabled.  I count a train that runs from Westbury to Southampton rather that from Swindon to Southampton as a cancellation as far as we're concerned in Melksham, as it fails to provide us with a service.

Where buses are provided in place of trains, I don't count them as cancellations if there's advanced publicity for it , as is happening nearly every Saturday and every Sunday at the moment.  But I do count last minute and unpublicised switches to buses or fleets of taxis - if you know who to ask when the train is "pulled"-  as cancellations.

I'm not personally too worried about a delay of a few minutes - especially on the 07:45 which habitually sits at the signal at Thingley when it's just left Melksham anyway - it's allowed for in the timetable. Even if it's 5 minutes late at Melksham, it will be on time by Chippenham