They drove the rest of the way into London in silence. Fortunately the rush-hour was starting to build, so Ace had to concentrate on manoeuvring the big four-by-four through the dense traffic. Finally they pulled up at the address in Perivale that Sanaul had given them.

As they stepped out of the car, the Doctor looked around the estate and frowned. ‘This looks familiar.’

‘It should be,’ said Ace pointing at the row of dark trees silhouetted against the clouds behind the houses. ‘That’s Horsenden Hill. Ring any bells? Cheetah people? Exploding motorbikes? The Master?’

‘Ah …’ The Doctor’s expression darkened. This had been the site of an epic battle with the Doctor’s arch enemy. A battle that had left its scars on both of them. That had had been 30 years ago for Ace. She wondered how long it had been for the Doctor …

Leaving the Doctor standing in the drizzle with her memories, Ace located the house where the girl and her family lived.

‘It’s that one.’ She nodded at one of the 1930s semis on the other side of the street. ‘How do you want to do this? Say that we’re here from the Government? From the TV company?’

‘How about we use this?’ said the Doctor, snapping out of her reverie and pulling a small leather wallet from the pocket of her coat and flipping it open. ‘Psychic paper.’

‘You what?’ Ace eyed the blank paper in the wallet suspiciously.

‘Shows the reader whatever I want them to see. Saves a lot of time.’

‘Very cool,’ said Ace. ‘I remember when you had nothing but a couple of spoons in your pocket.’

‘Oh, I’m all mod cons these days,’ said the Doctor proudly. ‘Psychic paper, sonic screwdriver, mobile phone, Corby trouser press … I’ve got the lot.’ With that she set off towards the front door of the house.

Wondering whether the Doctor might actually have a Corby trouser press magically secreted in her coat pocket, Ace hurried after her. She was about to suggest that she should do the talking when, before she could stop her, the Doctor reached out and rang the doorbell.

As the chime rang out inside the house, the curtains in the bay window twitched open and a man’s face appeared for a second before vanishing again. Moments later there was the rattle of a security chain and the front door eased open a crack.

‘Yes? What do you want?’ The man they had seen at the window was peering suspiciously at them.

‘Mister Eldon? I’m the Doctor, this is my friend Ace.’ She held out the wallet. ‘We were wondering if we could have a quick word with your daughter?’

Mr Eldon stared at the proffered wallet for a second, and then closed the door.

Ace groaned, mortified at the clumsy way that the Doctor had made their introductions. She might claim to be a different Doctor, but some things obviously didn’t change.