The clause, a key part of the Bill's intention to increase GM schools' powers and to allow them to open nurseries and sixth forms, came to grief when John Marshall, MP for Hendon South, left the committee stage of the Bill to attend a photocall with Norma Major, the Prime Minister's wife.
Seeing the Opposition were about to spring a vote, Anthony Coombs, the Conservatives' committee Whip, rushed after him, but then found that he too was locked out for the vote.
The Government said it would be able to restore the clause later, but Peter Kilfoyle, Labour education spokesman, said when the Bill returns to the House of Commons the Conservatives' majority will be at risk following one or possibly two by-election results.
There was talk this week that if Labour wins the Barnsley East by-election next month it could withdraw parliamentary co-operation, but while the loss of majority will affect the composition of committees, those already in existence will not change.
One senior Conservative said: "Even with a technical minority it should be possible to push the Bill through on the floor of the House."
The Government has so far passed parts of the Bill which will allow schools to introduce or increase selection without need to publish statutory proposals and require governing bodies to consider each year whether to introduce or extend selective admission arrangements.
In an earlier committee session, the Labour party was defeated on an amendment which would require a governing body to consider the effect of increasing selection on other schools in the area.
Estelle Morris, Labour education spokesperson, said: "No school is an island: no school can take decisions on admissions arrangements without having a wider impact."
There was also a lively compare-and-contrast discussion of Hampshire and Kent local authority performances led by Margaret Hodge, Labour MP for Barking. She noted that the LEAs have a similar socio-economic make up, but Kent has grammar schools and Hampshire does not. Kent's average of five A to C grades this year at GCSE is 43.7 per cent, Hampshire's is 46.5 per cent.
She said: "There are 11 schools in Kent, including four GM schools, which perform at a lower level than the lowest-performing school in Hackney, which is Homerton at 11 per cent."
She said the grammar schools were having an adverse effect on other schools in the county. "The structure in Kent is failing to deal with a long tail of underachievement."
* Sir Malcolm Thornton, chairman of the Education and Employment Select Committee, is to table a private member's bill on the setting up of a General Teachers' Council.
He came 11th in the ballot which allows MPs to put forward their own Bills and while it is highly unlikely to reach the statute book this side of the general election, Sir Malcolm believes it will air the issue in the House of Commons.
It is intended as an enabling Bill to establish the principle of a GTC.
Sir Malcolm believes the body, composed of elected teachers, heads, employers, parents and governors, would concern itself with professional development, career structure and training. It would also police professional standards and conduct.