Sunday promises to be the hottest day of the year – and the tensest

Rarely can the components for the perfect English summer weekend have been more exquisitely arranged in advance. The beers have been put on ice, the weather will be sizzling and the tantalising prospect of two days of sport await. What could possibly go wrong?

National life will grind to a virtual halt shortly before 3pm on Sunday when England take on Germany in South Africa in the World Cup. More than 20 million people are expected to tune in to watch the match on the BBC, hoping for the first win in the competition against the old rivals since 1966. It's an encounter that will leave roads, railways, and supermarkets ghostly quiet.

Thousands will gather at screens in city centres, in pubs and clubs and at the Glastonbury festival, where the match will be broadcast live to music fans. Those that refuse to join in can look forward to having the beaches to themselves, despite temperatures peaking at 30C around kick-off on what is predicted to be the hottest day of the year.

The pre-match war of words, like the high-pressure ridge responsible for the current heatwave, has already been steadily building on both sides of the North Sea. In Germany, the nation has been eagerly awaiting the prognostication of its most successful football pundit of the last two years.

Paul the "Octopus Oracle" has had an 80 per cent success rate and accurately forecast the national team's three results in the group stage. Yesterday the cephalopod confirmed bookmakers' odds by predicting a German victory when it selected a mussel with a German flag rather than an English one at the Oberhausen Sea Life Aquarium. The German media has been ramping up the rhetoric: the newspaper Bild listed six reasons why England's bid to make the quarter-finals will falter, based primarily on the team's dismal record of penalty-taking in top-flight competitions (particularly against Germany).

It also twisted the knife over England's goalkeeping woes, while the former German captain Franz Beckenbauer renewed his criticism of the squad, saying he believed the Three Lions had been "burnt out" by the punishing Premiership schedule.

Few can forget the penalties heartbreak of the World Cup semi-finals in 1990 or the fact that England exited in similar fashion in its last two major tournaments. But the man who could face them, David James, insisted the team could win in the normal 90 minutes. His teammate Jermain Defoe, whose goal put England through to the knock-out stages, was trying to stay focused on football despite learning yesterday that he will face trial on his return to Britain, accused of using a mobile phone while driving.

The Prime Minister, David Cameron, said he will be watching the match during the G8 summit in Canada and might even be sitting down for the second half of the crunch clash with the German leader, Angela Merkel.

"There is an idea we might try and watch it together. I will try not to wrestle her to the ground during penalties, but we will have to see," said Mr Cameron, who ordered an England flag to be flown from Downing Street before the tournament started.

The spirit of sportsmanship and diplomacy was also alive and well at the German Embassy, where the ambassador invited guests to watch the match with him at his London residence.

But even if the worst happens on the pitch in Bloemfontein, where the collapse of peace talks propelled Britain into the Boer War in 1899, police said they were not anticipating violence of the sort which marred the aftermath of the defeat in Italy in 1990 should England lose. A spokesman for Scotland Yard said it had no plans to deploy extra officers or cancel leave.