All companies in the UK must file annual accounts. They are available to anyone willing to pay the one pound fee per set of accounts.
Smaller companies don't need to publish P&L and cash flow. They can just publish a summary balance sheet. However, if you have the summary balance sheet for two consecutive years, then you can calculate the profit or loss.
About 60% of companies file accounts electronically using XBRL/iXBRL (rather than paper), and these accounts are available for free via daily/monthly zip files published on the Companies House web site.
Misunderstood accounts to mean customer lists... Got it, that's not too bad if its limited to financials. I guess the intent is transparency for trade partners/employees/etc. Thanks for clarification.
In the EU, you have to file annual financial report and sometimes consolidated reports. You may be required (or want to) to file other documents, depending on the particular circumstances. All those are freely available for an online check. All you need to know is the company's EIN - employer ID number.
[won't be up-to-the-minute accurate, of course, and won't work for all jurisdictions. But it's a data source that far too few people use, IME]