Merlin Entertainments has announced a half-year update on its operations for 2011 - reigniting rumours that the company might be planning a public listing sometime next year.

In a half-year review (six months to June 2011), chief executive Nick Varney offered no financial figures but said that the group had delivered against all six growth drivers outlined in an annual review published in June 2011.

He added that the group's Midway attractions portfolio (including Madame Tussauds, Legoland Discovery Centres and Sea Life Centres) were performing particularly strongly, with four new sites opening during the period.

Merlin is owned by three private companies - private equity giants Blackstone and CVC Capital Partners and Denmark-based KIRKBI that controls the LEGO Group.

Speculation over the possible stock market floating of Merlin has been rife in recent years. The volatility of the Eurozone, however, lead majority owner Blackstone to cancel the plans and instead sell a 28 per cent stake to CVC Partners in June 2010.