If a business is transferred from one owner to another your terms and conditions of employment, are automatically transferred as well. (The position with regards to pensions is more complex.)
Your rights derive from the Transfer of Undertakings (Protection of Employment) Regulations, commonly called TUPE. The effect is as if your contract of employment had been agreed with the new owner at the start of your original employment. Not only are your terms and conditions of employment transferred, but all the liabilities of the previous employer are also transferred.
If you were entitled to join, or were a member of, your previous employer’s occupational pension scheme, then, under rules brought in by the Pensions Act 2004, the new employer must offer you the opportunity to participate in an occupational or stakeholder pension scheme.
A transfer of shares only does not constitute a transfer of business for these purposes.
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