The last major overhaul of A-levels was in 2000

What are the changes the government has announced?

The main change, to the A-levels taken mainly in England, Wales and Northern Ireland, is threefold.

Firstly, questions will be more open-ended. For example, instead of giving students prompts:

The war began for three main reasons, what were they?

Explain why the war began.

Secondly, that greater attainment will be recognised with a higher grade, A*, on top of the present A to E.

But if the questions are harder, why do you need an extra grade? Will it not be more difficult to get an A grade anyway?

The problem here is one of continuity. If the questions were simply made harder, then attaining a certain level would indeed show a higher performance than now.

Putting it another way, an A grade after 2010 would be worth more than one attained this year or next.

The drawbacks to this approach are obvious. Politically it is unconscionable.

Instead, what will probably happen is that the exams will be "calibrated" following the trial version involving real students next year.

The aim will be to maintain the standard.

So if it required, say, 80% to get an A grade this year but the exam regulators decide that 70% on the new paper reflects the same level of achievement, they will move the "grade boundary" downwards to that point.

That is where the new top grade comes in. Someone who attains the 80% on the new, harder paper might be awarded the A*.

Will AS-levels have an A* too?

Good question and one that apparently cannot be answered yet. It was not mentioned in the government announcement.

AS-levels, which form the first part of an A-level as well as being a qualification in their own right, were introduced with the Curriculum 2000 reforms.

At the time the second part, the A2, was always meant to reflect the more challenging work in the previous A-level syllabuses.

So it might be decided to maintain that distinction, reserving the harder questions for the A2 only.

And the third change?

All students will be required to produce "an extended, dissertation-like project requiring independent research, thought and planning".

This was something also proposed to provide a greater challenge, allowing students to demonstrate an enthusiasm for a subject in greater depth.

Hand-in-hand with these changes, the number of modules that make up an A-level is being reduced from six to four. The extended project might account for one of those four.

What about the International Baccalaureate?

The government has said it wants at least one centre - probably a sixth form college - in each local authority area to offer the IB, as it is known.

Currently taught in about 1,888 schools in 124 countries including the UK, it is offered in 76 places in England, 46 of which are in the state sector.

The government sees its greater availability as giving young people "more high quality choice".

The IB has more breadth than A-levels but is not for everyone - it is regarded as academically demanding and logistically quite difficult for schools to teach.

Critics regard this as an elitist move by the government.

The University and College Union called it "another qualification aimed at those who are going to be high achievers anyway", whose expansion would merely add to confusion and the fragmentation of available qualifications.

Where does all this leave the Tomlinson diplomas?

Sir Mike Tomlinson's report in October 2004 proposed that GCSEs, A-levels and vocational qualifications should evolve over 10 years into a new diploma system catering for students at all levels of ability.

In its subsequent 14-9 White Paper, the government set out reforms to GCSEs and A-levels and proposed new Specialised Diplomas based on major employment sectors.

This was widely reported as "Tomlinson turned down", "GCSEs and A-levels to stay" and so on.

The first of those diplomas start in 2008, with others being rolled out to 2014.

Their implementation is not proving easy, and typically involves schools working with local colleges to acquire the necessary resources and expertise.

This is where it gets interesting, perhaps fanciful.

There are many in the qualifications business who think the response to Tomlinson was misreported.

That far from being sidelined, it is in fact where England's secondary education system is heading.

It is even now suggested that Mr Blair's enthusiasm for the International Baccalaureate - with its greater breadth and an already in-built extended essay, just as Tomlinson proposed - reflects his own pro-Tomlinson thinking.

A condition set out by the government for new centres wishing to be allowed to offer the IB is that they "will need to offer a balanced curriculum, including offering the new 14-19 Diplomas" (my stress).