Fields are:
LSOA ID  the ID of the LSOA in question. The ONS publishes the full boundary shapefile for all UK LSOAs on their website.
pre12 Time, in minutes, to travel to the closest open front counter at midday before the proposed March 2013 closures.
pre24  Time, in minutes, to travel to the closest open front counter at 4am before the proposed March 2013 closures.
post12  Time, in minutes, to travel to the closest open front counter at midday after the proposed March 2013 closures.
post24  Time, in minutes, to travel to the closest open front counter at 4am after the proposed March 2013 closures.

Note: A time of 600 minutes is an indication of an error, resulting in setting the time very high to make sure it does not cause a false positive (only a potential false negative). 