The 38-year-old Oxfam policy adviser scraped home by a margin of 0.02 per cent of the vote securing 7.42 per cent in a massive area stretching from Oxford to Brighton.
Her election ends 25 years for the Greens as the Cinderella of British politics and a long-awaited national representation begins to put them on the same significant footing as Green parties in France, Germany and other European countries. It will also be a massive boost for the environment movement throughout Britain.
"It is a historic moment," Ms Lucas said after the result was announced at 1am, following a three-hour count which hung on a knife-edge for most of that time.
Across the Channel the French Greens, led by the May 1968 student leader Daniel Cohn-Bendit, looked likely to achieve their highest score in a French election, at 9.5 per cent after a stridently pro-federalist campaign. The Greens outpolled the Communists for the first time, suggesting an historic shift of power on the French left.
President Chirac's Gaullists were the big losers in France. The turn- out was a record low of 45 per cent and voters punished most main parties - except Lionel Jospin's Socialists - leaving French politics more fragmented than ever.
The predicted Gaullist score of about 13.3 per cent was the worst figure recorded by Mr Chirac's party in a nationwide vote. The principal victor was a breakaway Euro-sceptic party, led by the former Gaullist interior minister, Charles Pasqua, which looked likely to score about 13 per cent, almost as much as the Gaullists and their liberal allies.
The Socialist Party of the Prime Minister, Lionel Jospin, scored an unspectacular 23 per cent - enough to cement its position as the main force in the pink-green-red coalition governing France.
In the vicious "fascist primary" on the recently divided far right, Jean- Marie Le Pen and the National Front looked likely to score no more than 6 per cent, its worst result for 15 years. Mr Le Pen's former lieutenant and bitter rival, Bruno Megret, looked likely to score about 4 per cent, not enough to give him a couple of seats in Strasbourg.Reuse content