(As there are cases that remain sub judice, I will give only a general answer describing the disclosure process.)
How does discovery disclosure work for financial crimes?
Disclosure for all criminal investigations in England and Wales, including those in to financial crime, are carried out in accordance with Parts 1 and 2 of the Criminal Procedure and Investigations Act 1996 and its accompanying Code of Practice.
A full explanation is given in the Code, but put briefly: the police appoint a Disclosure Officer whose role includes reviewing and assessing everything held by the police, called "material", and passing details of all "relevant material" to the CPS appointed prosecutor.
There are four stages in the police disclosure process, called the 4Rs:
- Record
- Retain
- Review
- Reveal
These 4Rs overlap with three questions that require answering in order:
Q1: Is it "relevant material" to the investigation? If No, nothing further need be done. If Yes then Record and Retain it in a "durable and retrievable format" - write it down, save it to disc etc, keep it safe and in a place where it can be found.
Q2: Is it "sensitive material"? e.g. does it relate to informants, covert tactics, information given in confidence etc? Either way, two seperate schedules of relevant material according to its "sensitivity" are created.
The Disclosure Officer passes both schedules (and the actual material if necessary) to the CPS prosecutor who provides the defence with a copy of the non-sensitive schedule. The prosecutor also asks:
Q3: Does the material "undermine the case for the prosecution or assist the defence with theirs"? If No, nothing further need be done. If Yes, the prosecutor must disclose the material to defence, unless it sensitive and giving it to the defence is not, for example, in the public interest as it may jeopardise life, covert operations etc. The prosecutor and police then has to decide whether to drop the case or not in order to protect the reason for the sensitivity. (They may also apply to the Crown Court judge for a Public Interest Immunity certificate which - in very, very rare cases - allows a trial to go ahead in the interests of justice without the defence being made aware of material that may assist their case as long as the whole trial process is fair to the defendant.)
The defence, in addition to their copy of the non-sensitive schedule, can apply for sight or copies of and any material that they consider also undermines or assists but has not been disclosed to them by the prosecutor, and is necessary for their case. In the first instance this application is to the CPS prosecutor, but if it is refused the defence may apply to the trial judge for a ruling on whether it must be disclosed or not.
The overriding principle is ensuring a fair trial.
ETA:
It it possible for a party to such a suit to bring evidence to the court without providing the underlying data to the other party?
It is possible but the principles of a fair trial, disclosure and the continuity of evidence (what some call the chain of custody) coupled with challeges by the defence are supposed to ensure that the provenance and accuracy of evidence is properly tested and accountable at a Plea and Trial Preparation Hearing (PTPH) before a trial opens. Unfortunately, especially in highly complex investigations, this does not always seem to be the case.