Ripper Street: Amazon Prime Instant Video will air extended episodes

According to Digital Spy: 

Prime customers will be able to watch the new extended episodes from late 2014, with the show being cut down to fit an hour-slot when it airs on BBC One in 2015.

"We don't have a 60-minute slot to fill at 9pm," explained Chris Bird - Amazon Instant Video Film & TV Strategy Director.

"So we said to Richard [Warlow, series creator], 'We want you to write this season completely unencumbered. If you want to write a 70-minute episode, write a 70-minute episode'.