Hello mad_jock.
You are right and wrong. To be given a caution means that you must first admit the offence, and then agree to be given a caution. And as you say the Police can take this into consideration should you come to notice again.
Also as you say, if you don't agree to be cautioned then the Police have no choice but to charge you and send to court.
"9 times out of 10 if the police know they have enough evidence to secure a prosecution the caution will not be on offer. So if you do get one offered it usually because they know they are on shakey ground and the PF won't go ahead or because of social and economic reasons the whole proccess is going to cost more in police time and court costs than would be recovered. "
This is not correct. For the Police to give a caution then they must have sufficient evidence to secure a successful prosecution at court, (on the basis that if the person does not agree to be cautioned then they have to be charged and taken to court.)
"The caution system is there so they can quickly record your wrong doings without using up court time and money. Then when you have taken the piss to much they get you for the whole lot in one go. They might only charge you with one offense but the sheriff will take into account you have been naughty before when sentencing you."
Up to a point that is true. But they are there for first time offenders to give them a 'chance' before going down the court route in the hope that they will learn from their mistake. People with past convictions almost never get cautioned. Also this only applies to simple petty offences. Someone for robbery would never get cautioned and neither would drink drive type offences.
"I don't think the central computer system in England records the cautions so any cautions are only available locally where you got Knicked. So if you have been cautioned in England it won't show up yet."
This is not correct I'm afraid, all cautions, whether adult or juvenile, are recorded on the Police National Computer and have been for at least 20 years, probably a lot more.
As you say it may be the difference between the Scottish Law and English Law.