The length of notice someone is entitled to when they leave or are sacked from their job, generally depends on your contract of employment. In the absense of anything in the contract of employment, the amount of notice set down by law is one week.
An employer may dismiss you without notice for serious misconduct, although you can contest whether the employer was justified in such action.
Your father may now consider taking a case of unfair dismissal to the Employment Appeals Tribunal, provided he is not among those people excluded from doing so. As Clubman mentions, there is a good document on the Oasis site about unfair dismissal - a good general overview of unfair dismissals procedures, how to take a case and information on how employers must be able to demonstrate that dismissal is justified.
You will generally require one year's continuous service to bring a claim under the legislation, although there are specific exceptions to this. The claim must be made within 6 months of the dismissal, although this can be extended in exceptional circumstances to 12 months.
As regards salary matters, I presume your father should receive all pay for work done and pay for untaken holidays up to the date his employment was terminated.
Your question is an interesting one, given your father has been employed by this firm for 15 years. Had he ever experienced difficulties before?