An article published in "Great United Songs" a publication created by Manchester United fanzine Red News, in January 2005:

We have always begun each Great United Songs volume with our most poignant of songs, the Flowers of Manchester. It's origins are now clear. It was sent into a folk magazine "SING", anonymously, in October 1958. The words were printed, but no music accompanied it, apart from a note saying it was to the tune of High Germany.

The folk group the Spinners (led by United fan Mick Groves) started to sing it and anyone who has heard their live version played to a solemn packed out crowd in a Liverpool club on one of their albums can't fail to be moved. Mick Groves told Red News that his proudest memory of Flowers is the night I sang it quietly in a corner to Sir Matt and Louis Edwards.

Red News stalwart Teresa McDonald was determined to find out who had penned this moving tribute. At a jazz festival in Italy she met the ex-Spinners penny whistle supremo Tony Davis. Teresa wrote in RN at the time:

As soon as lunch was over I got Tony in a corner and asked him about the Flowers authorship. No problem, he said, he told me shortly before he died he'd written it.
Who?
Eric Winter, the Editor of Sing magazine.

He said Eric had written it in early 1958 and it was published anonymously in SING in October 1958. Tony said it was the custom for folk singers to write anonymously because it gave more credence to the material.

He added that after the inquiry into the disaster, Mick Groves changed some of the lyrics. (The inquiry to clear the name of Captain James Thain took eleven years and actually involved 4 inquiries two British and two German.)

Returning to England I contacted Cecil Sharp House The English Song and Dance Society who very kindly sent me copies of the original published version in SING in October 1958 plus the music to High Germany and some biographical data on the (to me) unknown Eric Winter.

Winter's 1958 version has many different lines and words to the now more well known latter version that has appeared in all the Great United Songs. Some verses show that it must have been penned in the immediate days that followed the tragedy.

Tony Davis also said that Ewan McColl collaborated on the Spinners version the Great United Songs rendition which could go some way to explaining why for so many years rumours had it that McColl was the author. After all the years of trying to track down the authorship of Flowers of Manchester, the Guardian backed this up for Eric Winter's obituary on 31st October 2000 which clearly states that his song, The Flowers of Manchester, prompted by the 1958 Munich air disaster, was recorded by The Spinners.

UPDATE March 2010..I received an email from Tony Davis

A very small amendment to your notes about the song. I didn't actually EVER say that Ewan collaborated in the composition of the song. When Mick began to sing the original version, he based his MELODY on Ewan's version of High Germany. This fitted so well and eventually became the recognised tune for the song. I rather think that poor Eric was never quite happy with it however!
https://theflowersofmanchester.co.uk/history/

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