Question: Vera Lynn 100 is a compilation album that features collaborations with a an English tenor and actor, notably performing in what?

Context paragraphs:
The Little Boy that Santa Claus Forgot: "The Little Boy that Santa Claus Forgot" is a 1937 song written by Michael Carr, Tommie Connor and Jimmy Leach; most notably performed by Vera Lynn.  It is also known for the use of her version in the opening scene in Pink Floyd film "Pink Floyd—The Wall".

We'll Meet Again: The Very Best of Vera Lynn: We'll Meet Again: The Very Best of Vera Lynn is a compilation album by English singer Vera Lynn.

Vera Lynn 100: Vera Lynn 100 is a compilation album by English singer Vera Lynn.  The album was released on 17 March 2017, by Decca Records, to celebrate Lynn's 100th birthday.  Some of her best-known songs have been re-orchestrated for the album, which features original vocals.  The album features a previously unreleased cover of "Sailing", and collaborations with singers Alfie Boe, Alexander Armstrong, Aled Jones and Cynthia Erivo.  The singer also performed at a charity concert on 18 March, to raise funds for her children’s charity.

Her Greatest from Abbey Road: Her Greatest From Abbey Road is a compilation album by English singer Vera Lynn, released on 10 March 2017, by Parlophone and Warner Music UK to mark her 100th birthday.  This album compiles Lynn's recordings from Abbey Road Studios for the first time on a Vera Lynn collection.

Don't You Remember When: "Don't You Remember When" is a song written by Lynsey de Paul and Barry Blue, that was released as a single by Vera Lynn on 13 February 1976 on the EMI record label.  The song was recorded at the Marquee Studios, London and was produced by de Paul and she also sang backing vocals.  Ringo Starr, who was de Paul's boyfriend at the time, played the tambourine on the song.  De Paul also produced "That Old Feeling", the B-side of the single.  Tony Hymas, who had worked with de Paul before and would go on to be a member of the duo Ph.D., arranged the song.  De Paul was interviewed about how she wrote the song with Barry Blue especially for Vera Lynn after appearing on Lynn's TV show, as well as details about its recording in an article the UK music magazine, "Music Week".  Lynn and De Paul held a press reception at the Dorchester Hotel in February 1975 to announce the release of the single.  The song appeared on CD for the first time in 2007 as a track on the Vera Lynn compilation album, "Singles Collection".

DJ Premier Presents Get Used To Us: DJ Premier Presents - "Get Used To Us" is a compilation album by American hip hop DJ and record producer DJ Premier.  The album was released on his Year Round Records on December 7, 2010.  It features collaborations from frequent DJ Premier's collaborators and a few new comers.  The album was well received by critics.

Smoky Dawson: Smoky Dawson AM MBE (19 March 191313 February 2008) born as Herbert "Herb" Henry Brown, was an Australian country music performer, radio star, entertainer, and icon.  He was widely touted as Australia's first singing cowboy complete with acoustic steel string guitar and yodel, in the style of American Gene Autry: Dawson had an extraordinarily long and prolific career, releasing his first single in 1941 and his last album in 2005, aged 92, making him at the time the world's oldest recording artist (now surpassed by Dame Vera Lynn who released an album aged 97, in 2014).  Through his high-rating syndicated radio serials (at their height broadcast on 100 stations) television appearances, comic books and songs he created the persona of a happy-go-lucky singing cowboy".  An Australian institution, he continued to perform and march in annual ANZAC day ceremonies right up to his death a month shy of his 95th birthday.

Alfie Boe: Alfred Giovanni Roncalli "Alfie" Boe (born 29 September 1973) is an English tenor and actor, notably performing in musical theatre.

Rina Ketty: Rina Ketty (1 March 1911 – 23 December 1996), whose real name was Cesarina Picchetto, was an Italian singer, notably of the legendary song "J'attendrai".  The song reached superstatus during WW2 and was appreciated by Allied soldiers and Axis soldiers alike (equalled only by Lale Andersen's "Lili Marlene" and perhaps by Vera Lynn's "We'll meet again".)

A Future for the Michel: A Future for the Michel ("Eine Zukunft für den Michel") is a compilation album supporting charity by Moya Brennan and Schiller.  The album was released in December 2005 to raise money for St. Michel's Church in Hamburg.  The compilation features collaborations between the two artists and solo works.

Supporting paragraphs: Vera Lynn 100 Alfie Boe
Answer: musical theatre