As one of the top men at MI5 and MI6, writer David Bickford had an intimate knowledge of the intricacies of the British secret service.

Here, he explains how he believes Sussex can win the war on terror.

Tremendously successful was how police Superintendent Steve Voice summed up Exercise Woodchat on April 25 .

He was speaking as director of the exercise involving Sussex Police, emergency services and local authorities which imagined Sussex being pelted with debris from a mid-air collision.

With 30 million passengers a year passing through Gatwick airport and suspects from Crawley still remanded on terrorist charges, the exercise was a crucial test.

We should take great heart from his words because underlying them are the hours of planning, foresight, practice, liaison and sheer hard work of the 1,000 personnel who were directly involved and who are responsible for protecting the people of Sussex.

Hidden deeper behind the exercise are the members of the intelligence agencies, MI5, MI6 and GCHQ.

They pick hazy information out of the fog that is Al Quaida (or other terrorist groups) to create a picture of what is going on. That picture is like a faulty satellite television screen, flickering, fleetingly visible with halting, fuzzy audio.

Watching it is the Joint Terrorism Analysis Centre, which combines the expertise of the agencies, the police and other relevant organisations to analyse the picture, adjusting it to create more clarity.

Its job is to try to ensure exercises like Woodchat never become a reality.

It is very good at it, as its recent work has shown.

Eliza Manningham-Buller, head of MI5, and Metropolitan Police Commissioner Sir John Stevens have both said a terrorist attack is not a question of if but when.

These words explain starkly the magnitude of the task that faces the agencies and law enforcement.

They come as a bucket of cold water after the recent high profile arrests of terrorist suspects.

But as Sussex Chief Constable Ken Jones says, terrorists live among us just like any other criminal, so we can make a real difference by being vigilant and becoming more dependent on each other.

No list can be made of what we should look out for. Douglas Hurd, the former Home Secretary, said national security was like a tiger in the jungle - "You know it when you see it".

Suspicious activity is rather the same and we shouldn't be worried about reporting it. We should, however, be worried about discrimination.

Terrorism has no ethnic or religious relevance. Terrorists are a tiny minority of extremists who are shunned by the rest of the human race to which they claim to belong, whether they are English, Irish, Sri Lankan, Muslim, Christian or Jew.

If we can be like intelligence officers, calmly and dispassionately assessing the information stream, there are other areas where we can help.

Terrorists need transport, so car or van sales and hire firms can get to know a bit more about their customers.

A tiger spotted in this jungle could mean a terrorist foiled. Terrorists need money, so they are into drugs trafficking, illegal migrants, fraud, internet fraud and extortion.

They launder their cash, often through small shops, mini cab firms, cafes and then on through banks, property agencies, lawyers and insurance companies.

People working in these areas can also get to know their customers and watch out for any unusual cash sums or odd transactions.

As for drugs, the cash paid for Es or coke can find its way to paying for the next suicide bomber, who kills and maims the kids in a disco somewhere else.

It is sometimes difficult in this new battle to take in the international dimension of terrorism.

English law and its procedures, which we treasure, no longer give us the protection we have relied on.

So, to paste up the cracks in our system, we see suspect terrorists detained without trial and talk of lowering the standard of proof in terrorist trials.

This lack of respect for the rights of terrorists merely breeds more sympathy for them and more recruits.

Across the water, the French have a brilliant system of law to tackle terrorism which both succeeds in putting the terrorists behind bars and respects their rights.

The Privy Council recently recommended this system to the Government.

But because it is French it has been rejected.

If we are to isolate the international terrorists and win over their sympathisers we will have to look beyond our own shores and internationalise our response.

If nothing else persuades us of this, the thought of thirty million passengers a year passing through Gatwick should.

Which brings us back to Exercise Woodchat. That success was no flash in the pan. It mirrors the calibre of the police, emergency services, intelligence agencies and others who protect us.

For our part, the one piece of information we report might be the key they are looking for to help drive the terrorists out.

David Bickford is launching his new thriller The Face of Tomorrow at Borders, Brighton, on May 12 at 6.30pm.