The handbag of God

When homeless people seem lazy, sleep seems a waste of time and sex even more so, you're ready to pl

Thatcher left a provocative taste on the nation's tongue both politically and domestically, whether it be the stale emptiness of hunger, or of the now soured cream atop a Black Forest gateau bought with new money . . . Yes, the handbag of God touched us all.

As my right foot reached the tarmac of the parking lot outside Great Meadow Productions, June 2007, and my left remained gripped to the carpet of an old black cab, I attempted to steady myself in pre paration for as graceful a descent as one can muster with three backpacks, six scripts and a satchel full of episodes of the former Yugoslavian hit TV series Tesna koza.

"Kevin" the cabbie craned his neck to spectate in silent satisfaction. Kevin had reminded me on loop round every bend from Borough that he knew where I was going and I didn't. As I spat myself out of the car he couldn't resist icing the sticky journey, caked in heat, by purring, "Now, have you got everything, love?" both sides of his mouth curling. I made my way into the cool tranquillity of a public toilet in the basement and began to talk to myself in the mirror. Once I'd stopped feeling the urge to punch Kevin, specifically Kevin, I then felt the urge to punch all men. And thus my understanding of Margaret Thatcher began.

"Go back to the literature" - Joan Didion

Many thank yous to Kevin later, the Great Meadow meeting having been successful, I found myself surrounded by great doorstops of cold, hard fact, with a sprinkling of fiction, most of them written by the good lady herself.

For Maggie, knowledge was as powerful as it had been for John Lilburne in the Fleet Prison during the English Civil War. For the actor, as Mike Leigh once told me, there are things one needs not to know, but, in some part of my psyche, Margaret Thatcher will always be prime minister. All through my childhood that was her job. My job was to complete the Lego space hub for a newly acquired caterpillar. My dad's job was to sell luxury Japanese cars to Geordies all day, then come home to my plastic construction site and tell me how great Margaret Thatcher was at her job, while my mum picked curtains for the new extension and my sister got her fingers jammed in the new VHS player.

The Grocer's Daughter was responsible for a significant boom in my household's economy during the 1980s, not least the upgrade from Betamax. It was therefore essential to attempt to forget everything I'd ever seen on Look North Tonight. I also realised after the first 50 conversations (enjoyable though they had been) that I should never tell anyone that my next role was Margaret Thatcher, especially men and drunk people at dinner parties. Everyone has an opinion.

Having studied the earliest footage available, I worked backward, chipping away at the shroud of preconception to explore the mental and physical enigma of this social-reform-hungry young thing, and here met the Margaret and the make-believe.

Playing "Kalina" the Croatian-Serb beautician by night, I spent the day in personal pre-production, dividing the 13-year journey to Finchley into three stages of her development - Innocence, Experience and Downright Ruthlessness - as the surest references to withstand a non-sequential shoot. When you're making a film for £2.50 you haven't got time to fanny about.

I sat in her bedroom on a soggy Sunday, stared out of the crescent window at Grantham below and thought, "Why not? Why not get the fuck out of here?" I smelled the worn, wooden fixtures from the shop below. I remembered having championed an ecclesiastic debate in church that day and anticipated the completion of darning my right sock before returning that night.

I was nearly apprehended for trespassing at her grammar school one morning, uninvited and skulking around for Roberts's residue, my escape not helped by my last-minute, conspicuous clothing choice of Iron Maiden T-shirt, violet leggings, and tutu the previous night as I'd rushed from the theatre to King's Cross.

"I am staying my own sweet, reasonable self" - Margaret Thatcher

It's strange when it happens. And it happens overnight. I started to stop "doing" her. Homeless people seemed lazy. Men began to irritate me. The sinking of the Belgrano seemed entirely justified. Sleeping became a waste of time, sex even more so. I developed a neck-jerk response to the dull question, "How does one balance a home life and a career?" My face made a smile but my eyes no longer wanted to follow suit. A new pair of eyes had opened within, and this time they were true blue.

"The people of Britain need to learn to eat their own two feet" - Spitting Image's Margaret Thatcher

Sympathy is human. Some might argue this is proof that Margaret Thatcher is the devil. The glimpse of an Oxfam poster, and penning that plea to Gordon Brown for Darfur asylum-seekers is back at the top of my list of priorities, but a couple of days pass and my letter drawer remains unleafed. That, my friends, is sympathy - shallow, dirty, Hallmark sympathy. Empathy is something different.

It's an extraordinary thing to feel the struggle of a woman who seemed so hopelessly alien, to feel every one of your nerve endings alive with tenacity, to believe above all else in social reform. Whether society at large feels it important to understand what really made the young Iron Lady tick or not, I certainly gained an invaluable understanding of how my childhood home - and many others - came to be Thatched.

Andrea Riseborough starred in "Margaret Thatcher: the Long Walk to Finchley", broadcast recently on BBC4