The first thing you notice about Downing Street is the unobtrusive security. No doubt metal bars have sealed off access from Whitehall but the Bobbies on duty are friendly and chatty. They spend their time nattering with tourists who, in turn, are hoping to catch a glimpse of No 10's famous occupant.
When I arrived last Friday to interview David Cameron I was convinced getting in would take ages. So I turned up way ahead of time. In fact, it took barely a minute.
A policeman at the barricades consulted a list of names on a clip board. "We're expecting you, sir," he smiled. "You're early but you're better off waiting inside."
And with that I was in. A brief metal detector check was all that remained. No physical frisking, no form-filling and certainly no questioning. They knew why I had come and promptly and politely ushered me in.
As I approached No 10 it suddenly struck me the street was empty and there was no one at the door. It seemed more like an empty house than the official residence of the British Prime Minister. So I doubled back to the Bobbies at the junction of Downing Street and Whitehall. "What do I do when I get to the door?"
"Use the knocker and bang on it, Sir. Someone will open it from inside."
That's precisely what happened. A young Bobby, dressed informally without his black jacket and his sleeves half rolled-up, greeted me with a smile. He seemed friendly and relaxed. Behind him I could see pristine but empty rooms. Perhaps it was so quiet because it was lunch time. But the silence was beguiling. Actually, calm and soothing.
Shortly afterwards a member of the PM's staff, a young man called Mathew, asked if I wanted to see the house. "You've got a bit of time and the place is worth a dekko." I jumped at the opportunity. It was more than I was hoping for.
We went up the grand staircase with pictures of all the past 52 prime ministers. The first was Sir Robert Walpole in 1721. Winston Churchill is the only PM to have two. However, the one on the landing has been replaced by a picture of The Queen. "It's her jubilee," Mathew chuckled. "But he'll be back soon."
As I peered down the corridors opening off the staircase I couldn't help notice how vast the place was. From the outside No 10 looks like a small London terrace house. But it stretches a long way back. In addition, it opens seamlessly into No 11 and 12. The result is a large rambling house across several floors. I counted at least four.
Traditionally the PM lives in a little flat at the top of No 10. But the last ones to actually do so were Margaret Thatcher and John Major. Tony Blair, with a big family, took over the Chancellor's home at No 11. Since then Brown and Cameron have chosen to live at No 11.
The interview took place in 'The White Room'. "It's where the PM meets visiting heads of government," Mathew said. "But once upon a time it was Churchill's bedroom!"
Cameron did three interviews on the trot. They were in adjoining rooms so he didn't have to travel far. He arrived on his own although his press adviser slipped in quietly after him. She squatted on the floor in a corner. Everyone around Cameron was relaxed. He most of all.
Views expressed by the author are personal .