Many providers may claim to offer the highest levels of data security and data protection, but this only becomes more obvious with any further details they can provide about this.
Compliance with GDPR and the Data Protection Act are minimum requirements, along with more standard security provisions such as firewalls, anti-virus and encryption in transit and at REST. But if you’re to gain the greatest level of security assurances about how your data will be managed, accessed and stored, you need to look out for accreditations such as ISO27001 and Cyber Essentials Plus. And if they can offer any extra security assurances that meet the needs of a particular industry such as the NHS Data Security and Protection Toolkit, for healthcare, that will be of huge value.
In addition, you need to ask where your data is hosted. A provider may be UK based, but host your data in a different country, which is subject to different laws, potentially posing serious implications for the security of personal data. You would be much better off with a provider that stores and provides backup of your data on UK based servers.