It will be the first time since he lost his Bath seat at the 1992 general election that Mr Patten, the newly appointed EU commissioner for external affairs, will speak at such a gathering.
His plans to speak at the Conservative Group in Europe meeting will boost left-wing Tories who have been disheartened by Baroness Thatcher's comment that she wanted to pull out of the EU.
Mr Patten, the last governor of Hong Kong, is likely to warn William Hague, the Conservative Party leader, to resist Eurosceptic pressure for a further lurch to the right. He previously signed a letter by several Tory grandees, which criticised Mr Hague for his decision to fight the next election on a pledge to "save the pound".
They wrote in The Independent last year that it was "important that EMU [economic and monetary union] should succeed and for Britain to prepare now to join a single currency", language very similar to that adopted by Tony Blair.
The Conservative Group in Europe, chaired by the former cabinet minister John Gummer, is part of Conservative Mainstream, an umbrella group for pro-European Tory groups, which will hold several fringe meetings in Blackpool.
With Europe likely to dominate the agenda again, right-wingers such as Lord Tebbit are expected to address meetings of the Campaign against a Federal Europe and the Conservative Way Forward, many members of which want to "renegotiate" Britain's EU membership.
Lady Thatcher's remarks came under attack by left-wing Tories yesterday. They issued a warning against letting "misguided sectarians" hijack the party. Andrew Rowe, the MP for Faversham and Mid-Kent, accused the former prime minister of making repeated misjudgements, adding: "I really cannot believe that anyone seriously wants to open up renewed divisions in the party at this time."Reuse content