Invasion, that's the one. Your turn!
You already explained some of the clues, but here they are:
Clue 1: A band of which Maiden are known admirers have released a concept album with a homage to a person whose name can be made up with names of individuals who have played in Iron Maiden. This person is related to several bands. One of these bands has a name that connotes strongly with both the name and the lyrics of this Maiden song.
Marillion (who Dave says he likes in a TV interview). Marillion's 1987 album "Clutching at Straws" is dedicated to rock manager and mover-and-shaker in general, Tony Stratton-Smith (Tony Moore, Dennis+Adrian). Stratton-Smith signed the folk rock band Lindisfarne to the Charisma label in 1970. The island of Lindisfarne was the site of the first recorded Viking raid in 793.
Clue 2: The lyrics of the song contains the name of two different tv series, which are thematically linked.
"Vikings" and the excellent mock-Viking show "Norsemen".
Clue 3: A band that has numerous associations with Maiden have released two albums with names similar to Iron Maiden songs. The band's very first single has a name that is an obvious clue to the Maiden song in question.
Praying Mantis. Ex-members Bob Sawyer, Stratton etc. being one apparent link. The albums are "Sanctuary" (2009) and "Legacy" (2015). Praying Mantis’ first single was called "The Soundhouse Tapes Part 2".
Clue 4: Both bands referred in clue 1 have released songs with the same name as two Maiden songs. These two Maiden songs appear on the same album, one is the album closer. One of the many associations between Maiden and the band in clue 3 has an anniversary these days.
Marillion’s “Hooks in You” (1989), Lindisfarne’s “Mother Russia” (1993). Maiden were on the bill with Praying Mantis on the Metal for Muthas tour, which began 40 years ago, on February 1st, 1980.
Clue 5: The song can be found on more than one Maiden release. The name of the song is also a part of a name given to an unofficial release of Maiden material.
"The Soundhouse Tapes" and "Women in Uniform" B-side. “Invasion of Rarities” is a 1994 unofficial release with the Soundhouse Tapes songs, plus some other stuff. Also, I believe a bootleg from Maiden’s first European show in Belgium is called "Invasion".
Clue 6: The band name in clue 1 that “connotes strongly with the name and lyrics” of the Maiden song is similar to a geographical name.
See clue 1.
Clue 7: Within the lyrics of the song there are references to criminal offences, a means of transportation, and a gathering.
“Raping and pillaging” etc. ”Longboats”. “Muster the men from all the villages”.
Clue 8: To elaborate on clue 7: The subject matter of the lyrics is one that is addressed in several Maiden lyrics. The lyrics furthermore contains references to a mythical creature, an ominous signal, and (at least) two American football teams.
Battle, warfare. "Looking like dragons in the dead of the night”. “Beacon is burning”. Minnesota Vikings. Las Vegas Raiders (and Seattle Dragons, for good measure).