By the standards of the time

When I was studying for the stringent exams I needed to pass in order to obtain the Museums Association Diploma (a qualification to join a profession that later turned out to be too unremunerative ) I was undecided as to whether to take the oral practical exam in social history or science and technology. Not having been good at maths or science at school, I plumped for the former. So the day came. I was presented with a table of domestic bygones, silver spoons, iron firebacks and other blacksmiths' productions of uncertain vintage. And whatever I said about telling the objects' stories made sense. It was one of the exams I managed to pass first time.
After all, it was the 'story' in it that first drew me to history.
At that time I was looking after a collection of old gramophones and phonographs. Mechanical music machines that combined the arts of the clockmaker and carpenter. Beautiful and obscure. I wrote a book about them that has been in print for most of the last twenty years and sold around 10,000 copies. It's pretty popular, of its type. Maybe its success is because I wanted to bring the machines to life, to describe the human context in which they were sold and used.http://www.amazon.co.uk/Gramophones-Other-Talking-Machines-Library/dp/0747801045
Later I worked in providing photographic and digital access to unique and rare items in the 'paper museums' of the British Library and the Bodleian Library.
Holding a piece of paper, or a machine, or a wax cylinder - still smelling like a fresh wax crayon - is a tremendous link to a past world. The durability of objects, compared to the frailty of life, is something fascinating. As Betjeman put it

And the iron knob of this palisade So cold to the touch, is luckier now than he.
 

But beyond that there is the question of what would the people of those times be like? How much really would we have in common with them?
Even a hundred years ago - the days of Captain Scott and World War One - there was a physical toughness to life that seems daunting now. A man might lie in a shellhole on the Somme with a shattered thigh all day, and write to his brother what a grand view he had of the army going forward (this happened to my great grandfather). Boys fought and played at fighting, and humour was practical and rough. The importance of 'character' and stoicism is something we have lost now, in favour of  attributes such as good communication skills and empathy.
In writing fiction - in my two novels - I have flirted with the historical novel form. I have provided a medieval narrative and a Victorian narrative. Each is bracketed with scenes of modern researchers, is perhaps only viewable *through* the modern researchers' efforts. Do my historical characters really exist in their own right?
If we consider a young woman of the fourteenth century, the difference in outlook is almost unbridgeable. If she indulges in creative work, perhaps writing songs or poems, can we really imagine with any authenticity where that creative spark comes from?
In Anya Seton's Katherine, a well spring to so much of my creative thinking over the years, Geoffrey Chaucer appears as an individualistic romantic poet. Who knows whether he was really like that, or a social climber who used his cleverness with rhyme to ingratiate himself with royalty?
And leaving that aside, what of the sheer violence of those days? If our young woman happens to be the daughter of a knight, or the fiancee or lover of a knight, she has bought into that part of society whose God-given duty was to fight. The knightly class were mainly concerned with the codification and preservation of violence. For all their talk of chivalry, once hostilities in the Hundred Years War reached one of their periodic pauses, the knights would stay in France, rampaging through the countryside seeking free quarter.
John of Gaunt, the medieval Rhett Butler as pictured by Anya Seton, made up in brutality for what he lacked in the military competence of his older brother Edward the Black Prince. 
Leaving women and children to die in the wake of his scorched earth Chevauchee, such a man would now seems to operate with the moral code of such as  Dale Cregan, the Manchester cop killer.
So the pursuit of true authenticity seems ultimately fruitless. Or at least for the good characters. You could write a historical novel with authentic villains. The authentic Gaunt would have made a good villain.

If we met one of those people from a hundred or six hundred years ago, would we really understand them, even if we can understand their machines or their handwriting?

Investing a historical novel with the superstructure of a research plotline - ie making it 'timeslip' -aims to give it an extra authenticity, like the patina on a card long carried in the wallet. By providing less history, I have aimed at more historicity.
However I have not embraced  the 'truth to genre' that helps you fit into the commercial world. One of these novels is facing self publication - Perhaps the second will also have to 'leak out' that way too.

To be a really successful historical novelist - Bernard Cornwell or Elizabeth Chadwick for example - I am wondering if you are writing of the world of reenactment. The world of modern people in period clothes, with period weapons and some period attitudes - class distinctions, 'cruelty lite', but mostly just people like the Sealed Knotters who spend blissfully enjoyable weekends fighting and singing and drinking.
And before anyone thinks I am ridiculing reenactment, I have to point out this is something I did myself for a similar period the old National Service. And like a national serviceman, I learned a lot about my fellow man, and made some firm friends.

 Perhaps the next book will be a straight historical...