The law in England states that no more than 4 persons can own the same lease of land.
When collectively buying the freehold (clubbing together to buy out the landlord with your fellow leaseholders), it is customary to set up a limited company. This company owns the freehold title and may be limited by 'share capital' or more commonly by guarantee.
Share capital companies issue share certificates to company members, which represent each leaseholder's share of any profit or loss made by the company. With most freehold and 'right to manage' companies however, there is little or no profit and changes of company members make re-issuing shares impractical.
Companies limited by guarantee are a more popular choice because there is just a simple register of members to maintain.