SHORTLY after 9pm on Saturday night to the cheers of hundreds of English football supporters a lone youth shinned up the 20ft plinth on the statue of Major General Sir Henry Havelock in Trafalgar Square and tore down the last two flags placed there by Scotland fans.

Minutes later a crowd of about 300 English supporters, many of them football causals who had been taunting Scots all day, surged into the square, past police, chanting ``England, England''. Only a spray-painted slogan - Free Scotland - on the base of Nelson's Column bore witness to the ugly scenes that had taken place and to the fact the Scots had been there at all.

They had been, and a very small section of the 400 or so were organised football hooligans. They did not wear team colours, mingled with ordinary fans, and tried to damage the good reputation the Tartan Army has built up over the years.

In a long hot and extremely tense afternoon, in front of thousands of foreign tourists, the centre of London was for a short time transformed into a riot zone. I watched as police wearing protective vests and carrying batons, sent in mounted officers and brought dogs in to keep rival groups apart. I also saw a number of Scots suffering from the effects of CS gas used on them by police officers.

It was the nightmare scenario, which had been feared since the tie between the two countries was announced. Although there was only a handful of injuries and relatively few arrests the damage it did to the reputation of the Euro96 Championships was real enough.

The trouble erupted shortly before 6pm as most ordinary Scots supporters were still trying to make their way back from Wembley Stadium - and long before large numbers could have got to central London.

With Scots clustered around the base of Nelson's Column, the traditional meeting place for the Tartan Army, a group of about 30 chanting Chelsea casuals entered the area from below the church of St Martin-in-the-Fields. The police were unable to stop them and both sides charged towards each other scattering barriers and almost overwhelming the officers before they were pushed back and reinforcements called in.

There were also large groups of English casuals roaming freely on the streets of central London, clearly spoiling for a fight and making it extremely dangerous for the Scots supporters who wanted to leave. For a time they could not do so anyway as the police had taken the decision to seal the square off with the Scots inside.

In the streets immediately around the square small groups of English football hooligans were clearly visible. They mingled with tourists, taunting Scots and looking for a chance to get at them.

For their part the Scots initially responded well to being besieged. A few hundred around the base of the Nelson's column sang and chanted.

However, there were casuals among them, taunting police and rival fans and threatening press photographers. It is believed a number travelled from Aberdeen and Falkirk without tickets for the game and in the sole hope of causing fights.

As the tension rose the situation was in serious danger of getting out of hand. Bottles were thrown from the square into the police, press and passing traffic. In response police then made a number of baton charges into the Scots, arresting a handful of supporters.

Injuries seemed minor. A bloodied and battered Scots fan was taken from the square with his forehead cut open and his nose clearly broken, he was immediately surrounded by television cameras, but he had simply fallen off one of the stone Lions. An army medic went down, in one of the charges and was stretchered out, but it was not clear whether he had been hit by a bottle or by police batons.

During the evening officers sprayed CS gas into the crowd, six supporters were treated for the effects and others were taken to the fountains by friends in an attempt to wash the gas from their faces.

The evening had had its surreal moments and throughout the most agressive clashes between police and fans Japanese couples could be seen sitting in the square seemingly oblivious to what was going on. Open topped buses went by with holidaymakers taking pictures and one American couple were overheard saying ``It's just like Braveheart''.

The English casuals viewed the affair as the retaking of Trafalgar Square and said they were insulted by the fact the Scots were there.

Michael Baldrey, 29, a carpenter from Portsmouth was one of the first into the square when the Scots moved out. ``These Jocks come down here and take over our square,'' he said. ``They put their sleeping bags down. It's disgusting.''

Many Scots did find themselves trapped in the square and unable to get out. Fraser MacDonald, 22, said the whole thing had been ``unbelievable''. ``Why are the English behaving like this,'' he said. ``I was in a pub drinking with English supporters after the game and there was a great atmosphere. I come down here, we're just supporting our national team and they charge at us.''

Lucy Bailey, 19, from Glasgow, said she was angry at the police behaviour. ``They were coming into the square charging at us with truncheons, but we weren't doing anything.''

DUNCAN BLACK writes: Supporters arriving home from London yesterday claimed the skirmishes had been an isolated incident in an otherwise trouble-free weekend.

Their impression too was that the problems had been caused by ``casuals'' rather than genuine supporters, and that most of those responsible were English.

Members of the Tartan Army trooping off planes at Glasgow Airport said the real fans had been well behaved at the game and elsewhere in London.

Tom MacKenzie, 29, and John Grant, 27, both from Cumbernauld, were in the Trafalgar Square area on Saturday evening but left as soon as they saw trouble beginning to brew.

They said: ``It looked as if they were casuals who had arranged to meet. I think they were mostly English. There were police everywhere, mounted police and dog handlers. But the rest of the time in London was fine and the behaviour was good.''

Richard Sale, 24, and Calum Muirhead, 32, both from Penpont, Dumfries-shire, did not hear about the Trafalgar Square trouble until yesterday morning. ``All the Scots supporters we saw when we were in London were in great form, all well behaved. Some of them were very drunk - but still well behaved.''

Stephen Hawthorne, 35, from Bothwell, and Brian Jamieson, also 35, from Strathaven, said they had not seen any trouble in the city. ``The atmosphere at the game was great. We were eating sausage rolls with the English fans at half time. There were no problems. The behaviour of the Scots fans was excellent.''