Keeping each other in sight, Joe and Armitage made their way through the crowds until, emerging on the other side, both men stopped to take a deep breath and stare at the open green spaces about them.

‘The lungs of London, they call them, sir,’ said Armitage with something very like the modest pride of ownership. ‘And what with Kensington Palace on one side and Buckingham Palace on the other, London’s lucky to have it still. You’d have thought it would have been pinched for the palaces long ago.’

‘Don’t think they haven’t tried!’ said Joe. ‘George the Second’s wife – Caroline, I think she was? – once had the nerve to ask the Prime Minister what it would cost to enclose the whole of the three big London parks for the exclusive use of the Court. Wise old Walpole replied, “Madam, it would cost you three crowns: those of England, Ireland and Scotland.” She didn’t pursue the idea.’

Armitage grinned, enjoying hearing the old story repeated.

‘There’s the Serpentine.’ Joe pointed to the gleam of the lake ahead of them, glimpsed through the thickening trees. Stately elms and groves of silver birch sported fresh green foliage as yet undarkened by soot. Joe suddenly grasped Armitage’s arm and pointed. ‘Look, Bill, do you see it? There!’

Armitage was puzzled.

‘A wood-wren!’ said Joe. ‘I’ll swear that was a wood-wren.’

‘Looked like a sparrer to me, sir,’ said Armitage repressively.

‘Listen. What can you hear?’ Joe persevered.

‘Nothing . . . silence . . . No, I can hear traffic in the distance . . . kids screaming down by the lake . . . birds . . .’

‘Birds!’ Joe shook his head and grinned. ‘There speaks a city boy. There’s a blackbird, and that’s a mistle thrush, a . . .’ Abruptly Joe’s pleasure in his surroundings faded. ‘And . . . someone calling for help. Listen! Did you hear it? I’m sure I heard –’

‘Over there – behind that scrub.’

They both began to run towards the sounds of distress. A female voice wailing and then a second voice, female this one also but louder and peremptory and calling for help, drew them on.

Joe was beginning to outdistance Armitage when he spotted a large man, running from the scrub towards the main carriageway leading to the exit. He was red-faced and lumbering along slowly, hindered by a considerable beer-belly and a preoccupation with the fastening of his trousers which appeared to be gaping open. Head down, he was too concerned to outrun the figure chasing after him to catch sight of Joe as he pounded forward to intercept him. Tilly Westhorpe, face like an avenging Fury, elbows pumping and heels flying, was hurtling with the speed of a miler, closing rapidly on her quarry.

God! What would the girl do if she caught up with this barrel of lard, Joe wondered? Six strides later he found out. With a whoop of triumph, she launched herself at the man’s ankles and brought him crashing to the ground. Before he could struggle to his feet, she had plonked her nine stone frame firmly on top of his head. Taking a whistle from her breast pocket, she was about to emit a blast when she noticed the arrival of the cavalry. She seemed pleased to see Joe.

He sat down without ceremony on the man’s flailing feet. ‘Good morning, Westhorpe. Are you going to tell me who we’re sitting on? Who’s your friend?’

‘Fiend, more like!’ she panted. ‘Been trying to catch him for weeks, sir. Rapist of the worst kind. Normally attacks females after dark, those stupid or desperate enough to come out here at night, but the supply of idiots has dried up lately and he’s taken to daytime attacks.’

A foul cursing made its way upwards through several layers of serge skirt. Westhorpe bounced briskly, banging the man’s head on the ground. ‘No swearing!’ she said. ‘Lady present!’

‘Er, I think you could get up now, Westhorpe. Don’t want to afford the reprobate a further frisson of an arousing nature, do we? Too much excitement for one day, perhaps?’

Armitage had arrived and was taking in the strange scene, mouth sagging slightly. ‘Ah, Sergeant! Your handcuffs, please,’ said Tilly. ‘And then, if you wouldn’t mind – there’s a poor girl in the bushes over there who will be needing our attention. It’s all right,’ she added, seeing Armitage blanch, ‘I think I disturbed him before worse occurred. And perhaps you could do the honours here, Commander? Female constables do not have the authority to make an arrest.’

Knee in the man’s back, Joe cuffed him. He informed him that he had been arrested by a Scotland Yard Commander and was on his way to the Hyde Park police station to be formally charged. The imposing arrival of two plain clothes detectives on the scene appeared to take the wind out of his sails and, abashed, he began to whine explanatory, man-to-man excuses. ‘. . . only a bit o’ fun . . . just a skylark . . . you know how it is, sir . . . but who can tell what these silly cows’ll say . . .’ His whine turned to a howl as the sharp edge of a police boot caught him across the shin.

‘Westhorpe!’

‘Sorry, sir, but you didn’t seem to be about to oblige.’

Armitage joined them. He was carrying in his arms a slight, sobbing bundle. Thin white arms were clasped around his neck. Stick-like white legs protruded from a short black skirt, ending in red socks, and one black patent-leather shoe dangled from a toe. Joe saw the expression of concern on Westhorpe’s face before she could compose herself to look at the victim.

‘Says her name’s Vesta, miss,’ said Armitage.

‘Vesta,’ said Westhorpe gently. Joe noticed that she took off her police hat to talk to the girl to avoid frightening her further. ‘Hello, Vesta. I’m with the police and these gentlemen are detectives. You’re safe with us. Vesta, are you feeling strong enough to identify this person as the man who attacked you just now? Don’t worry, it’s just a formality,’ she added, ‘and he can’t do you any more harm.’

A tear-stained face looked up from Armitage’s tweed waistcoat and glowered through a thick fringe at the prisoner. A small, accusing finger pointed.

Her shriek startled Joe. ‘That’s ’im! That’s the whoreson, great pile o’ pig-shit! I know ’im! It’s my dad’s cousin ’Erbert. Just let ’im wait till I tell my mam! She’ll fillet ’im! She’ll ’ave ’is cockles off and feed ’em to our cat! An’ where’s my other shoe got to?’

Joe and Armitage exchanged long looks.

‘Shall I propose that we drop this little lot firmly into the lap of whatever lucky inspector is on duty over there in the station this bright a.m.?’ suggested Joe.

Chapter Seven

Two hours later Joe was easing his Morris Oxford Cabriolet down Upper Brook Street looking out for Tilly’s home. With an embarrassing grinding of gears he spotted it and slowed down. Armitage winced. Joe could not be certain whether it was his boss’s driving skills that so irritated the sergeant or the aristocratic appearance of the spacious Georgian house in front of which they had just rolled to a halt.

‘This looks like it,’ said Joe, heaving on the handbrake. ‘Hop out, will you, Bill, and sit in the back. I’ll go and let them know we’re here.’

‘I think they’ll have heard you, sir.’

The front door opened to reveal Tilly Westhorpe remonstrating with an elderly man. The silver-haired, straight-backed figure, of perceptibly military bearing, seemed to be losing an argument with the uniformed Tilly. She gave him a swift kiss on the cheek and stepped eagerly down the short path to the car. Joe opened the rear door and handed her over the running board and into the back seat.

This was not a social occasion and etiquette was unclear but, dash it all, what were good manners but an expressed consideration for others? On impulse, Joe turned and walked up to the house, swept off his hat and bowed his head briefly with a disarming smile. ‘Sir, I cannot drive off with a chap’s daughter without introducing myself. Commander Joseph Sandilands. We spoke on the telephone this morning. I’ve been advised by Sir Nevil to make use of Mathilda’s special skills in a particularly distressing case –’