All UK registered companies are legally required to have a UK registered office address.
It is the address of a company to which Companies House letters and reminders will be sent.
HMRC, the UK tax authority, will also contact the company through this address. The registered office address can be anywhere in England and Wales (or Scotland if your company is registered there).
It should be a genuine location and suitable for delivering documents to the company.
It is also the address at which legal notices are officially served.

It has always been a legal requirement to display the company name at the registered office address.
In addition it should also be displayed clearly on company stationery and paperwork. This includes the following-

All the company’s business letters,All bills of exchange, promissory notes, endorsements, cheques, orders for money or goods purporting to be signed by or on behalf of the company,
All notices and other official publications, and all bills of parcels, invoices, receipts, letters of credit.

However, following the introduction of the Companies Act 2006 it is now a legal requirement to display your company’s registered office address on your website and any electronic communications.
Most people will put this information on their contact page of a website or on the footer of the home page.
If you have a trading address that is different to the