It all started with an email titled: "Can we stalk you?". As subject lines go, it's definitely one of the more intriguing.

It turns out it wasn't just a random request but a pitch tied into the DVD release of London Spy - the superb spy drama starring Ben Whishaw.

This stalking wasn't going to be a GCHQ-style mass surveillance operation but the chance to feel what it would be like to be professionally surveilled by Intime Investigations - as per the murky overtones of subtle surveillance that are found throughout the series.

The "up to two man" team would be using, among other things, a Canon EOS 5D Mark III and a Mobius DVR camera to track my movements and that was all I was told. No drones here - well, not to my knowledge anyway.

What was I thinking?

"What was I thinking?" This was my first thought after I volunteered for this, but then I adjusted to the idea. Yes, I was going to be spied on but it would be interesting to see how modern surveillance compares to both our cultural fears and the ideal of the quintessentially English James Bond spy, of which London Spy inherits a cultural nod.

I was given a date range of three days - Monday to Wednesday - and a window of six hours in which I knew activity was going on. And, well, that was it. I didn't know what kind of surveillance would occur or how deep it would go.

Would there be photos, video? Or even phone tapping? What about those drones? The possibilities half horrified and half fascinated me.

It's surprising how utterly paranoid you get knowing that someone might be lurking, watching. Immediately, I wondered: will I get that instinctual 'someone's watching' feeling? What should I wear, do I want to look 'nice' for my photos (ugh, really? But, yes, the thought crossed my mind)? Should I try and lose them? Boy did I want to try, as natural instincts kicked in over those three days.

I even wondered if I should approach complete strangers to signal somehow if I thought I had rumbled them.

Most of all I wondered if, for the sake of this piece, I was violating my own privacy massively by even writing this up, as I didn't want to invite further attempts by internet randoms to 'do a better job'.

Peak Paranoia

Monday arrived. The surveillance may or may not have begun. I conveniently had a doctor's appointment early before work, so I hoped they'd pick Monday to follow my movements as I had a quiet few days planned otherwise.

Walking to the doctor's I scanned the street and noticed a man ahead of me on the opposite side of the road, in a dark mac, not taking the bus like everyone else.

He wasn't walking with a purpose but he was dressed professionally, and his pace stayed in time with mine until he turned off the main road as I entered the doctor's surgery. I couldn't spot anyone else obviously waiting, but then again, it was early.

The day continued and my imagination clearly got the better of me. The thing about surveillance is that if you know it's happening you will react, you can't help yourself fluctuating between "for god's sake act natural" and "evade, evade, evade!". My workmates gently teased me as I regaled them with stories of who I thought I might have spotted on the commute in.

The scarier thing, however, is if you don't know you're being watched. No feminine instincts, no glaring "man with a camera", it's called covert surveillance for a reason.

My hyper-awareness had ramped up and, to be honest, it was exhausting. The experience made me realise we normally walk around with a head in our phones, or phones in our ears, without really looking at who's around us.

We use our phones to communicate in public with hardly a thought to digital privacy when the potential to snoop is vast, a potential to record, log and trace your entire life.

A heightened paranoia followed me over the three days, but I was also half expecting to get a call from the PR, saying: "Psyche, we're not really following you!".

Tuesday came and the questioning continued. Was it the man who just lurched onto the bus in a rush, looking like a retired police officer in a black windbreaker and fitted ear piece no civilian would wear, clutching a coffee who then followed me halfway across London on the District Line? Maybe.

What about the casually-dressed teenager looking disaffected and bored with sunglasses on sitting opposite who seems to be staring at me behind them? Definitely... Maybe.

I even thought I was being tailed by someone using a briefcase hidden camera. So much so, I dropped back behind them as another commuter blocked its view, and I mirrored the commuter's steps down the rest of the road to try and keep out of sight. What had I become?

It was tiring and I'm sure it made me look like an idiot or a pickpocket. Despite the adrenaline, I was getting tired of feeling twitchy and normalcy eventually got the better of me so that by Wednesday, I had given up thinking I was being followed.

Then I received my surveillance pack from the London Spy team. My three-day binge of paranoia had, of course, been pretty much unfounded. Yes, I had been followed but only a few pictures were taken of me going about my day. There was a little composite video too but nothing massively invasive. This wasn't a 24/7 operation, even though my brain going overtime made it feel like it was, but they had successfully managed to surveil me at three key points in my day.

There was one video, however. It was of me on a train going to work and it was almost certainly taken by someone who I spotted while in my fug of suspicion, I am sure of it. Definitely… Maybe.

As that old t-shirt slogan goes: 'Just because you are paranoid doesn't mean they are after you'. The fact that governments have access to even more sophisticated surveillance technology, made me realise that it takes a certain person to want to live in that world which London Spy captures so well.

And, even in the current climate of digital surveillance overstepping and Apple lawsuits, that person certainly isn't me.

London Spy is out now on DVD courtesy of Universal Pictures (UK). Watch the featurette below: