There are special rules for PLCs, which include:
Only a PLC may offer shares or other securities to the public, and a company must be a PLC to be listed on the Stock Exchange or Alternative Investment Market (AIM). Some aspects of the Companies Acts apply a stricter regime to such companies.
The registration of a PLC is a two stage process. The first stage is similar to registering a private company limited by shares, but the company must apply for a second certificate (usually called a "trading certificate") when it makes a return to Companies House stating that the company has raised its initial share capital. Check that you have all the required information and register your PLC on-line now.
Many PLCs are not registered from scratch but are converted from existing private companies. Company Law Solutions offers this re-registration service.