22/10/2013 08:59 BST | Updated 21/12/2013 05:12 GMT

How is Spying and Surveillance Evolving?

By Jonathan Digby, author of A Murderous Affair.

One of the many remarkable things revealed by the NSA spying revelations is how remote from the subject of their surveillance spies have become. Programmes with enigmatic names like XKeyscore or PRISM scan mainframe computers in far away bunkers, collecting and sifting through reams of emails and searches, which disconcertingly reveal to faceless bureaucrats our most intimate thoughts and intended actions. Of course there are still 'agents' in the field, but on the whole this method of spying bears little resemblance to the Cold War espionage that many of us grew up on and which is highlighted so cleverly and dispiritingly in the novels of John Le Carré.

In fact, the dead letter boxes, codes and tradecraft of that era appear to have far more in common with the roots of modern espionage in the late 16th and early 17th centuries, than they do with the digitally enhanced version of the 21st century. Then the task of the intelligencer, a term first used in the 1590s, could not be completed without eyeball-to-eyeball contact and the spies were adept at 'conversation'. As today, words, both written and spoken, were the currency of the trade, but the balance was very different.

Though a certain amount of information came from intercepted letters, more came through intimate dialogue - at dinners or religious meetings, in inns and prisons - between those who often believed themselves to be talking to someone on the same side. Elizabethan spying, more than anything, was defined by the art of the double agent or even triple agent - men, and women, who operated in a twilight world between opposing sides.

The beneficiaries of this duplicity, sitting at the centre of these ragged spider webs, were some of the great men of the age - Burghley, Leicester and above all Sir Francis Walsingham, the Queen's Principle Secretary - a title that poignantly contains the word 'secret'. Walsingham's network, consisting of Cambridge MAs, poets, priests, and prisoners - all cajoled, bullied or bribed into service by their determined master - was the envy of his contemporaries.

One can only surmise at what a man like Walsingham would have made of the new technology but I imagine he would have welcomed it whole-heartedly bearing in mind his motto that: 'there is less danger in fearing too much than too little'. As it was, he collected as much intelligence as he could from his networks, in one year receiving over 500 letters from some 50 foreign-based sources. Just before he died in 1590 he received material from twelve places in France, ten in Germany, as well as from the Low Countries, Germany, Italy and Switzerland - small fry, perhaps, compared with today but impressive nonetheless.

Walsingham was no angel - he also opened plenty of private letters, as evidenced by his masterful manipulation of the Babington plot. And like today's internet 'connectors', he tapped into the broadband of his day, the official 'post'. Nevertheless, he targeted those that he believed to be a specific threat to the life of Queen Elizabeth.

Perhaps what makes us most uncomfortable about today's remote version of espionage is that, unlike with Walsingham who generally targeted perceived dangers, we are all now blanketed as such, simply because we communicate.

Jonathan Digby is the author of A Murderous Affair, published by Endeavour Press.