Question: On which British BBC Radio 4 soap opera do Felicity Finch and the 12th Earl of Portland star?

Context articles: Felicity Finch
Fi Glover
Ruth Archer
Graham Roberts (actor)
Timothy Bentinck
Phil Archer
Ian McIntyre
Colin MacDonald (writer)
Nelson Gabriel
Tracy-Ann Oberman

Felicity Finch (born 14 March 1955) is a British actress, known for her Tyneside-accented portrayal of Ruth Archer in "The Archers" on BBC Radio 4.
Fiona Susannah Grace "Fi" Glover (born February 1969) is a British BBC journalist and presenter who currently presents "The Listening Project" for BBC Radio 4, "Shared Experience" for BBC Radio 4 and "My Perfect Country" for the BBC World Service.
Ruth Archer (also Pritchard) is a fictional character from the British BBC Radio 4 soap opera "The Archers", played by English actress Felicity Finch.
 She made her debut in the 15 July 1987 episode.
 The character was created and introduced to "The Archers" as a love interest for established character David Archer (Timothy Bentinck), whose then girlfriend was deemed unsuitable for the role of mother to the next generation of the Archer family by the editor of the show Liz Rigbey.
 Finch was cast as Ruth after a successful audition.
Graham Roberts (10 October 1929 – 28 October 2004) was an English actor best known for his work on BBC Radio 3 and BBC Radio 4, including 31 years playing George Barford, the gamekeeper in Radio 4 soap opera "The Archers".
 He was born and raised in Chester, and was educated at King's School in the city.
 Later, he studied at Bristol and later Manchester University.
Timothy Charles Robert Noel Bentinck, 12th Earl of Portland, Count Bentinck (born 1 June 1953 in Tasmania, Australia), commonly known as Tim Bentinck, is an English peer and actor, most widely known for his long-running role as David Archer in the BBC Radio 4 series, "The Archers".
Philip Walter Archer is a fictional character from the British BBC Radio 4 soap opera "The Archers", played by Norman Painting.
 He made his first appearance on 29 May 1950, the show's pilot episode.
 The character later became the longest serving male character in the series.
 His longevity gave him something of the status of a 'patriarch' in Ambridge.
Ian McIntyre (9 December 1931 – 19 April 2014) was a British BBC Radio producer, journalist, broadcaster and author.
 who was Controller of BBC Radio 4 from 1976 to 1978 and then Controller of BBC Radio 3 between 1978 and 1987.
Colin MacDonald was born in 1956 in Inverness, Scotland.
 He is a prolific writer for television and radio.
 Television credits include "The Dunroamin Rising" (BBC1), "The Gift" (BBC1), "The Wreck On The Highway" (BBC1), "Sharpe's Honour" (ITV) and episodes in the series "Blue Murder" (ITV), "Heartbeat" (ITV), "Casualty" (BBC1), and "Para Handy" (BBC1).
 Radio credits include "Killing the Butterfly" (BBC Radio 4), "Hill of Rains" (BBC Radio 4), "The Colour of Summer" (BBC Radio 4), "King Of Hearts" (BBC Radio Scotland), "" (BBC Radio 4) and "Calum's Road" (BBC Radio 4).
Nelson Gabriel is a fictional character from the British BBC Radio 4 soap opera "The Archers".
 He was portrayed by Jack May.
Tracy-Ann Oberman (born Tracy Anne Oberman, 25 August 1966, Brent, Greater London) is an English television, theatre and radio actress.
 Best known for her role as Chrissie Watts in BBC1 soap opera "EastEnders" from 2004–05.
 Also a writer, Oberman has contributed to a number of radio sketch shows and in 2008 co-authored with Diane Samuels the play "Three Sisters on Hope Street".
 In 2010 she wrote and starred alongside Catherine Tate in her BBC Radio 4 play "Bette and Joan and Baby Jane" and in 2012 wrote the BBC Radio 4 play "Rock and Doris and Elizabeth".
 In 2015 she wrote and starred in the third part of her Hollywood Trilogy for BBC Radio 4, "Mrs Robinson, I Presume", alongside John Simm and Kevin Bishop.
 Oberman was a regular columnist for "The Guardian" newspaper during 2007.