By Trevor Timpson
Two very different finds, dug up close to each other by Trafalgar Square, shine new light on the greatest puzzle of London archaeology - the "silent" centuries after Roman rule.
The Last Roman's grave (ringed) was found close to the Square.
That the skeleton of "London's Last Roman" - or anything ancient and unknown - can be discovered in 2006 in Trafalgar Square is remarkable.
But when it comes to yielding secrets, the square's church, St Martin-in-the-Fields, has a long record.
When the present church was being built in the 18th Century a body was found in a reused Roman stone coffin. And in the 13th Century the authorities had to step in after treasure hunters ransacked the then church in search of "a gold hoard".
So in 2006 it was assumed that the man in a limestone coffin - dug up in the space between Victorian burial vaults and the church's boundary - was also a later burial in a reused Roman sarcophagus. His head had been lost, probably in the 19th century.
Then the result of the radio carbon dating came back from the lab in Florida to which a small bone had been sent. With 70% certainty, it said, the Last Roman had died some time between 390 and 430 AD.
The grey pot and the burial: both remarkable, especially together.
To enthusiasts, the midpoint stood out - 410, the year that the hard-pressed Roman empire abandoned all claims to Britain. It was not a later burial at all.
Suddenly, says Francis Grew, senior curator at the Museum of London, there was "huge interest" in the find.
"We can say with some confidence that this is the latest scientifically dated burial from Roman London," he says.
Just metres away from where the coffin was discovered was something else which, if dug up in the garden, would probably be thrown away - a squashed, grey pot, hand-moulded, not made on a wheel, and with a crude decoration of lines and punch-marks.
"I assembled all the finds, laid out on a table for the first time," says Mr Grew, "and I got specialists from different fields and said: 'Tell me what you think of all this'."
He expected the Anglo-Saxon experts to show interest in the later Saxon jewellery found on the site.
Instead they went straight for the pot lying in fragments - grey and nondescript but massively important.
A type of pottery used by the earliest Saxon immigrants from northern Germany, it is dated to about 500AD - the earliest near-complete Saxon pot to have been discovered in central London.
This made the St Martin's dig hugely significant, shining a new light on the mystery of London's lost centuries.
Plenty happened in London in the 450 years following the end of Roman rule in 410. It became the seat of an English bishopric. Bede in the 730s called it "a mart of many nations".
The Anglo-Saxon town (Lundenwic) was west of the Roman Londinium
So why could archaeologists find almost no evidence that London was inhabited at that time?
It was not until the 1980s that they realised they had been looking in the wrong place.
The Anglo-Saxon London, Lundenwic, was not on the site of Roman London - what is now the City - but in the West End, around Aldwych, the Strand and Trafalgar Square. Then objects and traces of buildings which had already been found in these places began to make sense.
But still there was a 200-year gap. Even Lundenwic remains could not be dated to before the seventh century.
Now, with the latest Roman burial and the earliest Saxon pot found within metres of each other, the gap has narrowed to just 90 years - and set everyone thinking about what it means for the transition from Roman to English London and the significance of the St Martin's site.
The site was surely a prominent place in ancient times - raised up above the Thames with views back to the ancient walls of Londinium and down towards what is now Whitehall and Westminster. Its reputation as a place where treasure could be found was still notorious in the 13th Century.
But what did it mean to the two sets of people - the ones who buried the "last Roman" and the ones who owned the grey pot - who are now almost in sight of each other in the archaeological record?
One thing Mr Grew is sure of is that enough remained of the cemetery in which the Last Roman lay and other graves now lost, to make it clear that this was a very special place.
"Anyone coming there in 500 would have been aware of the notable remains - perhaps a brick mausoleum crumbling away," he says. A Roman brick-kiln has also been found nearby.
And if there was a religious, sacred site, could it have been Christian? When the Last Roman died, Christianity had been officially favoured in the Roman Empire for decades - yet there are few Christian remains from Roman Britain and no identifiable churches in Roman London.
For the vicar of St Martin's, Nicholas Holtam, the discovery of the burial of the Last Roman is a moving experience.
Brick-built cemetery near Rome: Trafalgar Square 500 AD?
The man was a contemporary of St Martin himself, Nicholas Holtam points out. And he believes there are signs that it may well have been a Christian burial.
It raises the possibility that St Martin's (first recorded in the 13th Century) has been a sacred site for much longer than we previously thought, he says.
He recognises that the evidence must be looked at scientifically, but adds: "I'd love it to be proved that this was a Christian site dating back to 410."
The Last Roman and the pot are both in The Missing Link display at the Museum of London until 8 August.