THE definitive history of the decline and fall of the Celtic empire at the end of the last century has still to be written.

But amid the rubble of a disintegrating club, there was a pillar of highly visible ineptitude. His name was Tony Cascarino. He was a million-pound centre forward who provided four goals before being sent on his way. He was the wrong player at the wrong club at the wrong time.

''I was bought to be Celtic's Mark Hateley,'' he says. ''Everything about the move from Aston Villa seemed right. Liam Brady, the manager at Celtic, was once my agent and was a friend. Celtic was my club in Scotland. It just seemed so right to go there.''

He admits candidly he was a failure, but lists reasons, not excuses. ''It was all down to me. I wasn't as fit as I could have been. In Scotland, it was Celtic and Rangers, and that was it. I missed the English league. The whole thing was a bad mix. I was playing badly and my confidence took a battering. It became so bad I didn't want the ball, I didn't want to play.''

He tells in his remarkable memoir, Full Time (Simon and Schuster, #9.99), of a meeting with a Glasgow punter in a supermarket. The fan berated him viciously and when Cascarino attempted to mollify him, believing his verbal assailant was a Rangers fan, the supporter ended his tirade with the words: ''You're crap and I'm a Celtic fan.''

Cascarino says: ''It was a bad time. My confidence was shot. Celtic were second best to Rangers. I fully accept it was all down to me. But, remember, when I was out of the side nothing really changed. Results didn't start to change because I was not playing.''

He does have some good memories of his brief, turbulent sojourn in Glasgow. ''I scored against Rangers, and Celtic fans still come up to me and congratulate me on that. I had never seen anything like the atmosphere at an Old Firm match,'' says the man who played for 19 years in England, Scotland, and France. ''It's passionate and full of hatred. It's like a war. I don't believe I have experienced as a player or a spectator anything quite like it.''

His epitaph to his Parkhead career is brief but powerful: ''I felt I let Celtic down. I felt I let Liam down. I felt I left myself down.''

The last statement is the nub of the Cascarino conundrum. He tells of his negative thoughts while playing for Celtic. This voice of an inner demon was to haunt him throughout his career. ''I always lacked a confidence,'' he says. ''There was always self-doubt. The Americans have recognised the importance of being mentally strong. I never adapted myself to this.

''My best mate at Millwall was Teddy Sheringham. Yet people forget I left Millwall before him. People wanted to sign me rather than Teddy. I should have taken confidence from this.''

He admits he did not have the self-assurance of his striking partner and friend. ''When Teddy took the penalty in Euro 96 he had already missed penalties for his club that season. Yet he still grabbed the ball and said: 'I'll do it.' He is mentally tough. I had no doubts he would succeed at Old Trafford.''

Cascarino's confidence may have been affected by his upbringing in St Paul's Cray, near Orpington, Kent. He encountered fear early. It happened in what should have been the safest haven in the world: his home. His father was a truculent, violent man. Cascarino was subjected to scant praise and regular beatings. It is one of the many uncomfortable aspects of a brutally honest book. Cascarino

has famously revealed he was not eligible to play for the Republic of Ireland, for whom he won more than 80 caps and played in two World Cup finals, but it is his revelations closer to home that bring a gasp.

He is candid about his divorce which was precipitated by an affair with a French woman. His wife discovered the worst by finding a fax in a hotel room from Cascarino's amour that informed the striker that he was to become a father again. Cascarino details the disintegration of the marriage which was finally laid to rest by a curt note from him left on a kitchen table. He walked away from his wife to find a new life in France.

The whole story is in his book. ''I felt I had to write about everything. I have read sports books and come away thinking I have not learned anything I didn't know before. I wanted this to be different. I wanted people to know the real me. I wanted to paint a picture so that people knew what I had done, what I thought, and how things went wrong. I would like my children to read it one day and perhaps it will explain things to them. The book is about life, about how we really are.''

He has married again and achieved a reconciliation with his father, but adds: ''He hasn't read the book yet and he may be unhappy with some of the things I've said.''

But Cascarino seems resigned to this. He has found an assurance which he only grasped at the end of his playing career. ''I think the turning point for me was signing for Marseille,'' he says. ''I was at a low ebb and decided that the way I was thinking had to change. I suppose I matured. I decided to go out all guns blazing. It was the end of my career and I was disgusted at my attitude. I said to myself: 'You will be out of the game soon if you keep on thinking like this.' ''

He grasped his future in both hands. When Marseille were awarded a penalty in his first match, he wrenched the ball from a team-mate and scored. It was instantly the new, improved Casca-rino. He became a French hero, labelled Tony Goal. Far from his critics in England and Scotland, Cascarino flourished.

''I scored two goals against Juventus that season and ran Jorgen Kohler ragged. He shook my hand at the end of the match and said he couldn't believe the change in me. I know some people in Scotland will find it hard to believe, but I received offers from Serie A clubs, but Bernard Tapie would not sell me.''

He went on to play the local hero at Nancy. But now, after 19 years in the game with Gillingham, Millwall, Celtic, Chelsea, and Aston Villa he has retired, bloodied but unbowed at 38.

When asked about his plans, he replies: ''The future is an illusion. None of us knows what is in store. My wife is expecting another baby. It's my fourth and now I have two families to support. I am not secure financially and I will have to find work.''

He is busy promoting his book and will then do his coaching badges. The unknown beckons. ''I am scared,'' he admits. But Casca-rino has faced down fear before. It is unlikely now to knock the once lumbering striker off his stride.

Extracts from Full Time: The Secret Life of Tony Cascarino.

After three months I had pretty much had my fill of the Scottish Premier League. Parkhead and Ibrox were magnificent theatres for

football but neither of the Edinburgh grounds were

anything to get excited about, and then you'd go to places like Falkirk and Airdrie and it was like playing in the lower leagues. The ongoing bullshit of the phoney war in the city was also wearing me down.

''Don't go to 'that' bookies again. That's a blue-nose bookies - if they realise you play for Celtic you'll be stabbed.''

''You can't play golf at that club. That's a blue-nose golf club. None of the Celtic lads go there.''

So you'd go to the ''Tim'' bookies and play golf at the ''Tim'' clubs and do your shopping at the ''Tim'' centres and be abused by the ''Tim'' supporters instead!

The final straw was when a couple of my team-mates slagged me off because ''it had been noticed'' that I'd been drinking with the Rangers players, Terry Hurlock and Ally McCoist. Why did I have to hate them because 'they' played for the other side.

After the 5-1 hammering at the hands of Neuchatel, Liam Brady confronted Cascarino in the dressing room

''What the f- is going on, Tony? You were a disaster! I've never seen you play so badly!

''Yeah, I dunno . . . I just . . . I was crap.''

It wasn't quite the response he expected. ''What,'' he exploded. ''You're actually admitting it!''

''Yes,'' I replied ''I am. At this moment in time, I'm a bad player. I'm playing crap.''

''Well, that's f-ing marvellous: I pay a million pounds for a player and three months later, he tells me he's crap! Thanks a f-ing lot.''

I showered and changed and joined the rest of the team on the coach ride back to our hotel, where we drowned our disgust with a couple of beers.