The romantic drama stars Sir Derek Jacobi and Anne Reid as a couple reunited after 60 years.
Written by BAFTA-winner Sally Wainwright, the show also stars Sarah Lancashire, Nicola Walker, Tony Gardner and Dean Andrews.
The second series ends tonight and fans have been told to expect a third series which will go into production in 2014, to be broadcast later in the year.
Wainwright said: “I’m so happy we’ve got a third series, it’s so exciting to be able to take these characters further and to find out loads more stuff about them.
“What’s so great about writing for characters like Celia and Alan is that there is a wealth of back story to explore. Series three will be a whole new emotional ball game.”
The drama has won two BAFTAs (Best Drama Series and Best Writer) and three RTS North West Awards, it has also been shortlisted for Best Drama Series at the Broadcast Awards 2014.