Question: Which TV adaptation featured one actor playing two separate parts throughout its 37 episodes?

Context articles: Brian Poyser
BBC Television Shakespeare
ISO 3166-2:SJ
Great Waldingfield
The Iceman Cometh (The Play of the Week)
Catalan Talgo
Kalininsko-Solntsevskaya Line
Fallujah Barrage
Dual role
Separation property (finance)

Brian Poyser (died 2009) was an English actor whose career started in the early 1960s.
 His appearances include the musical "Poppy", the BBC Television Shakespeare (including a senator in "Coriolanus", and Gower in "Henry IV Part 1" and "Henry V"), the series "Sex, Chips & Rock n' Roll", an episode of "Agatha Christie's Poirot", and as the recurring character the Revd Aubrey Stewart in two episodes of "Foyle's War" ("The French Drop" and "Plan of Attack").
 He also appeared in the films "Lady Jane" (1986), "Parting Shots" (1999), and as one of the English judges in the film "" (1999).
The BBC Television Shakespeare is a series of British television adaptations of the plays of William Shakespeare, created by Cedric Messina and broadcast by BBC Television.
 Transmitted in the UK from 3 December 1978 to 27 April 1985, the series spanned seven seasons and thirty-seven episodes.
ISO 3166-2:SJ is the entry for Svalbard and Jan Mayen in ISO 3166-2, part of the ISO 3166 standard published by the International Organization for Standardization (ISO).
 The standard defines codes for names of principal subdivisions of all countries coded in ISO 3166-1.
 Svalbard and Jan Mayen does not exist as an administrative region, but rather consists of two separate parts of Norway under separate jurisdictions—Svalbard and Jan Mayen.
 Further subdivision for Svalbard and Jan Mayen occurs under Norway's entry, , namely NO-21 for Svalbard and NO-22 for Jan Mayen.
 There are currently no ISO 3166-2 codes for Svalbard and Jan Mayen.
Great Waldingfield is a village and civil parish in the Babergh district of Suffolk, England about two miles (3 km) north-east of Sudbury and two miles (3 km) south-west of its sister village, Little Waldingfield.
 The village is split into two separate parts; the older and smaller part around the St. Lawrence Church, and the newer and larger section along the B1115 road between Sudbury and Hadleigh.
 Most of the houses in the newer section were built after World War II, including much council housing.
 The population is estimated to be 1,460, reducing to 1,431 at the 2011 Census.
 The parish also includes the hamlet of Upsher Green.
The Iceman Cometh is a 1960 television production of the Eugene O'Neill play of the same title.
 Two separate parts were originally broadcast as episodes of "The Play of the Week" by the syndication service National Telefilm Associates (NTA).
The Catalan Talgo was an international express train introduced in 1969 that linked Geneva, Switzerland, with Barcelona, Spain.
 It was named after the Spanish region Catalonia and the Talgo equipment it used.
 It was an extension and upgrading of a predecessor train, "Le Catalan", a first-class-only French (SNCF) "Rapide" train that had been in operation since 1955 but running only between Geneva and the stations nearest the Spanish-French border, connecting with a second-class-only "autorail" trainset to and from Barcelona.
 The national railway network of Spain, "Red Nacional de los Ferrocarriles Españoles" (RENFE), was using Iberian gauge for all of its main lines, while those of France and Switzerland use standard gauge.
 As a result of this break-of-gauge, train journeys between Geneva and Barcelona consisted of two separate parts, with travelers having to change from a French to a Spanish train or vice versa at the border—at Portbou (alternatively written as Port Bou) on southbound trains and at Cerbère on northbound trains.
 In 1968, this was resolved with the introduction of the Talgo III RD trainsets, which featured variable gauge wheelsets.
 At Portbou station, the wheel spacing of each passenger carriage was adjusted by a gauge changer for the difference in gauge, and passengers no longer had to change trains.
 After successful test runs, the "Catalan" was extended from Port Bou to Barcelona as a through train on 1 June 1969, becoming the "Catalan Talgo" and upgraded to a Trans Europ Express (TEE).
 Most other rail journeys through this border crossing continued to require a change of train at Cerbère station or at Port Bou, as most trains did not use Talgo III RD trainsets.
The Kalininsko-Solntsevskaya Line (Кали́нинско-Солнцевская ли́ния , ] ) (Line 8) is a line of the Moscow Metro, currently consisting of two separate parts.
 It was opened as the eastwards Kalininskaya Line in 1979, with the first stations of the western Solntsevsky radius opening in 2014.
 Presently there are 8 stations on the eastern section and 5 on the western section.
 The two parts are planned to be joined by 2020.
 To distinguish the 2 sections, the newer west section is identified as Line 8A.
The Fallujah Barrage is a barrage on the Euphrates near Fallujah in Al Anbar Governorate, Iraq.
 Construction of the barrage was completed in 1985.
 Unlike many other dams in the Euphrates, the Fallujah Barrage does not include a hydroelectric power station and its main function is to raise the water level of the river for irrigation.
 The barrage consists of two separate parts.
 The main stretch of the barrage has ten gates measuring 16 x , allowing a maximum discharge of 3600 m3 per second.
 The second part on the left bank of the river has eight gates that are 6 m wide.
 These gates divert water toward two separate irrigation channels.
 Their maximum discharge is 104 m3 per second.
Dual role (also known as double role) refers to one actor playing two or more roles, which may be deliberately scripted in a play or film, or merely be a by-product of a low budget.
 In a theatrical production where more than one actor plays multiple characters, it is sometimes referred to as an "Ironman" cast.
 In film and television, a dual role is commonly used either for comic effect or to depict identical twins.
A separation property is a crucial element of modern portfolio theory that gives a portfolio manager the ability to separate the process of satisfying investing clients' assets into two separate parts.