Stoppages in play are part and parcel of cricket, from the old favourites of rain and light to the more unusual such as swarms of bees and even the sun. But in August 1973 the Saturday of the Lord's Test was brought to a grinding halt by a bomb threat, and for more than an hour thousands of spectators milled on the outfield as the ground was searched.

Throughout the summer the Irish Republican Army (IRA), a terrorist organisation, had stepped up acts of violence against mainland Britain. In August there had been several attacks, including a letter bomb sent to a secretary at the House of Commons, and the country was on high alert.

On the cricketing front, West Indies arrived in July for a three-Test series after England had easily seen off New Zealand. After a few years of rebuilding, West Indies, under the veteran Rohan Kanhai, were beginning to emerge into the side that was to dominate world cricket for almost two decades. Their win in the first Test at The Oval nevertheless raised a few eyebrows and after a draw at Edgbaston the sides headed to Lord's with England still confident of levelling the rubber.

Those hopes were dashed on the first two days as West Indies ran up 652 for 8 and England closed the Friday on 88 for 3. On the Saturday, in front of a full house and in glorious late-summer sun, West Indies continued to turn the screw, and by the middle of the afternoon session England were 206 for 8 and facing the follow-on.

The atmosphere was positively Caribbean, with the large West Indian contingent, mainly in the grandstand or on the grass between boundary and stands, noisily banging drums and blowing horns and whistles to celebrate every success.

Then at 2.45pm, MCC secretary Billy Griffith announced over the public address system that there had been a warning given by telephone that a bomb had been planted inside the ground and on police advice Lord's would need to be evacuated. It later emerged this was one of many similar hoax calls made across London on the same day, and the MCC alone received 13.

As Griffith spoke, the players and officials were bustling towards the pavilion. They were prepared. England's 12th man had been sent out a few minutes earlier to warn umpires Dickie Bird and Charlie Elliott, as well as Kanhai, what was about to happen and what they needed to do. On a given signal Elliott was to pocket the ball, while Jim Fairbrother, the groundsman, had been told by Griffiths on that agreed signal he was to "get the covers on like lightning".

For a few minutes after the warning was sent out, play went on, although it was noted that the West Indies fast bowlers appeared to lose their bite against England's tailenders, and hurried arrangements were put into place. As Fairbrother and his staff started moving the covers, they were bombarded with jocular insults from the West Indian fans, who gleefully pointed to the sun and asked if he had lost his mind.

At the end of the over Elliott looked at the pavilion, nodded and popped the ball into his pocket and with a buzz of confusion humming round the stands as the players left the middle, Griffith spoke. Fairbrother's posse just beat the rush of spectators to the middle and got the covers over the Test pitch but the rest of the square, including the track for the Gillette Cup final a week later, was engulfed by people. "It was quite frightening for a time," Bird recalled, "as they swarmed towards us like a great incoming tide."

As Fairbrother, covers in place, reached the pavilion to see if there were any more instructions, one of the stewards pointed back to the middle, where Bird was sitting on one of the covers, surrounded by fans who were giving him their jokey views on his regular no-balling of the West Indies pace attack. As they pondered what to do, Kanhai reappeared down the pavilion steps telling them: "Don't worry, I'll get him."

Most people had headed out into the surrounding roads, others stayed put until politely but firmly persuaded to move on by the police as all the stands were slowly searched. After an hour the police gave the all-clear. The game could not resume immediately as the many thousands who had hung around had to be given time to get back to their seats, and it was an hour and three quarters before play restarted. Griffith and the umpires agreed that play would be extended by half an hour and then started 30 minutes early on the Monday to make up the lost time.

The surreal day still had a twist. England followed on and lost three wickets by the close. Each one prompted pitch invasions but joyful celebrations turned ugly when opener Geoff Boycott fell to an ill-advised hook off the final ball. As he headed off he was jostled and manhandled by several West Indians before the police were able to intervene.

"Boycott did not strike anyone in the melee," wrote Crawford White in the Daily Express. He fended off one persistent man more gently than I might have done under the same provocation."

"In some ways it was more unpleasant than the bomb threat," concluded John Arlott, "because it came from within the game itself."

What happened next?

• West Indies completed a massive innings-and-226-run victory midway through the fourth day
• The MCC immediately banned spectators from sitting on the grass following the incident with Boycott

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