Anyway--in short--nobody knows for sure where King Alfred's remains are now, and the last place anyone is sure of, his "last known resting place," was somewhere around the Hyde Abbey site.

"Rest" can be a euphemism for "dead." One traditional inscription on tombstones is "R.I.P." or "RIP," which conveniently happens to be the initials of the Latin phrase "requiescat in pace" and its English translation, "rest in peace." 

I wrote my earlier post simply based on reading the passage. Looking up King Alfred in Wikipedia, and then doing a Google Image search on "king alfred plaque" "hyde abbey garden" confirms my opinion:

https://en.wikipedia.org/wiki/Alfred_the_Great#Death.2C_burial_and_fate_of_remains

"Alfred was originally buried temporarily in the Old Minster in Winchester; then, four years after his death, he was moved to the New Minster... when the New Minster moved to Hyde, a little north of the city, in 1110, the monks were transferred to Hyde Abbey, along with Alfred's body... Soon after the dissolution of the abbey in 1539, during the reign of Henry VIII, the church was demolished..." and that's only the beginning of the story!

This web page
http://royalrestingplaces.com/2014/09/12/winchester-king-alfred-the-great/
says "Although his ‘whereabouts’ is well documented, a series of events now indicate that the content of this particular grave is dubious."
The memorial is a stone tablet embedded in the wall of the abbey ruins--they have a picture--and it says "SITE OF HYDE ABBEY 1110 AND BURIAL PLACE OF ALFRED THE GREAT HIS QUEEN AND THEIR SUN EDWARD THE ELDER."
The burial place is thus identified as being somewhere on the Abbey site, not directly underneath the tablet.

It means he was buried there. It means that the writer feels sure that King Alfred's remains (i.e. bones) <em>were</em> buried there <em>once, </em>but the writer suspects they are not there now. It's the last known resting place. They may be somewhere else now, but there's no good proof. It's the last place anyone is <em>sure</em> about.

His <em>last known place is commemorated</em> at Hyde Abbey Garden does not mean he was ever buried there. There is <em>something</em> at Hyde Abbey Garden, perhaps a bronze plaque, that <em>says</em> where King Alfred was buried. 

It usually means that this is where he is believed to have been buried  i.e. his body was 'laid to rest' here.  The King may have died somewhere else, and his body brought here for burial.

The word 'commemorated' means that his life and achievements are recognized and noted, so a person can be commemorated in the absence of physical remains.

Thank you, we have the same phrase.