William Blake's born in 1757, so he's born into disturbed political times when there were all kind of currents going on. Blake is wandering about the London streets wearing a red bonnet, which is a symbol of being a radical and being a dissenter, of being one of those people who are against the Monarchy, who see prophetic writings on the wall and this goes into the spirit of the French Revolution, which happens 1788/89 – a lot of the radicals in England respond to that – to the idea that you can get rid of the aristocracy, you can get rid of your debts, you can get bread, the social unrest of England is boiling up. There's a spirit of the American colonies wanting to throw off English imperialism, get rid of the King and Blake's writing reflects that.

There are riots, non-conformist riots, where Protestants in England are – working-class Protestants are whipped up in London to fear the Catholics. Blake is caught up in a mob, a London mob, that goes from Soho, where he lives, right through to Newgate Prison, where the prison doors are burnt with great apocalyptic scenes and Blake, the radical poet, witnesses this, he's not himself a revolutionary, but he would have been in danger of being hanged. This is a militarised city – people are frightened. It was rather like the London riots of 2011, when suddenly something disturbs the fabric of the city and people are joining in for all sorts of reasons. There are underlying senses of unrest and unease and disenfranchisement and Blake's writing comes out of that.

Another aspect of these times, apart from these revolutionary moments, was the Industrial Revolution – a different kind of revolution altogether, in which machines are beginning to replace workers and quite close to here, in Blackfriars Road, were the Albion Mills – huge flour mills – with machines made by John Rennie, turning out unheard of quantities of flour and therefore, threatening the working people and these mills were burnt down, I mean, in the same way that Newgate disappears. Whether this was arson or not, I don't know, but there were astonishing little publications, chapbooks and so on brought out about this with illustrations of the burning building and a spirit of fire and apocalypse that Blake finesses into his works, which he's making himself in Hercules Buildings – his home is his studio and his garden is The Garden of Eden and this Industrial Revolution is going along with the ‘dark satanic mills’, right on his doorstep. These are not just metaphors – these are facts about the condition of England.

Blake's poem, ‘London’, really touches on the social ills of the time which were there too. I mean, the fact that child labour was appalling, he was very taken with the figure of the boy chimney sweep, who he sets against often a snowy backdrop – the blackness of these children covered with soot, starving, deformed and legislation is brought in much later, which points out the fact that children are being employed as young as four, five, six and are being forced to go up these very narrow flues by having fires set under their feet, being poked and prodded and by the time they were twelve years old, they were described as little wizened old men – I mean, more or less thrown onto the streets. So, Blake's desperately aware of that – so he's someone of enormous passions and anger and these social ills which affect London, affect him deeply and work their way into his poems as metaphors. And the other aspect would be the level of prostitution – that the city is full of women who cannot make a living in any other way. It's a really – a nightmare city of the rich and the poor. Very much, as in some ways, it's going back to now. I mean crossing London this morning to come here – I'm near the City of London, I'm stepping over dozens of rough sleepers who are on the streets at the same time as the bankers are commuting into their offices and their new glass buildings. It is that sense of a schizophrenic city – city of terrible social ills that Blake touches. We're very close to the ground of Cumberland Gardens, where this Declaration was created, which householders had to sign to indicate that they were not radicals – they were not part of this – that they were part of the established system and they were obliged, door to door, to sign this document and were essentially pledging themselves to the established order and I don't think there's any record that Blake ever did sign it, though his household would have been visited obviously. Whether he managed to hide himself away and not become part of this, I don't know – but being in front of the MI6 building now, where these records are kept of all of us, and we're well aware of CCTV cameras panning everywhere, that this atmosphere, where the State wants to challenge and sort out and make yourself pledge, is still very much present, so coming back to this ground is quite a big moment I think.

In the poem, ‘London’, Blake uses the terms ‘chartered streets’ and ‘chartered Thames’ and the charter is this sense that we have to be given of permission to be in certain streets – we have to be there by charter, that the Establishment will do that and the chartered streets are streets, for example, whereby cattle would have been brought to Smithfield Market for slaughter and you would be allowed to have fairs, or stalls, or pubs, or brothels along these streets – they were chartered, so all those social horrors are there almost by charter by the Government allowing them. There is a sense, as with the signing of the Declaration, that you have to negotiate everything through a sort of official bureaucracy and it's a double city and it's the same as the chartered MI6 building, or the chartered cameras that are watching us everywhere we go across the city. That's why Blake is so relevant – in just that single word, slipped into that poem, sets it up and makes it a pivot into contemporary times.