If anyone listened for one hour then it appears that the file on iPlayer is not the file broadcast. And when was Hancock aired? Anyway the file from iPlayer states:

General
Complete name                   : C:\Downloads\The Radio Ballads Singing the Fishing 24-03-12.m4a
Format                           : MPEG-4
Format profile                   : Apple AAC audio with iTunes info
Codec ID                         : M4A
File size                        : 34.2 MiB
Duration                         : 36mn 0s
Overall bit rate                : 133 Kbps
Album                            : The Radio Ballads
Track name                      : The Radio Ballads: Singing the Fishing
Performer                        : BBC Radio 4 Extra
Genre                            : Podcast
Encoded date                     : 2012
Writing application             : Lavf53.6.0
Cover                            : Yes
Comment                         : Tales from the Norfolk and Scottish herring fleets with Ewan McColl's songs. Award-winning documentary from August 1960.

Audio
ID                               : 1
Format                           : AAC
Format/Info                      : Advanced Audio Codec
Format version                   : Version 4
Format profile                   : LC
Format settings, SBR             : No
Codec ID                         : 40
Duration                         : 36mn 0s
Bit rate mode                   : Constant
Bit rate                         : 128 Kbps
Channel(s)                      : 2 channels
Channel positions                : Front: L R
Sampling rate                   : 44.1 KHz
Stream size                      : 33.0 MiB (96%)

However this file is full length:

rtsp://rmv8.bbc.net.uk/radio2/radioballads/singingthefishing.rm

General
Complete name                   : C:\Downloads\BBC Radio - Radio Ballads - Originals WebRip (1958-1964)\singingthefishing.rm
Format                           : RealMedia
File size                        : 12.9 MiB
Duration                         : 55mn 49s
Overall bit rate                : 32.5 Kbps

Audio
ID                               : 0
Format                           : Cooker
Codec ID                         : cook
Codec ID/Info                   : Based on G.722.1, Real Player 6
Duration                         : 55mn 49s
Bit rate                         : 32.5 Kbps
Channel(s)                      : 2 channels
Sampling rate                   : 22.05 KHz
Bit depth                        : 16 bits
Stream size                      : 13.0 MiB