At A level you must use a very formulaic approach to jump the right hoop. Unconventionality like FadeToBlackOut suggested shows clearly that he's too old to give advice to A level students
We've had drilled into us that the introduction must be:
1 sentence background
1 sentence define key terms
1 sentence outlining the main focus of each paragraph.
For an essay "To what extent was Queen Elizabeth I succesful in securing her legacy"
"Queen Elizabeth I was monarch between 1559-1603, a long reign which symbolised a period when England went through fundamental change, socially, economicaly, politically and culturally. To assess her legacy it is necessary to consider how successful people consider her in a number of fields. She can be considered to be successful in controlling her Parliaments, in fending of internal threats and in securing England's economic status. She can be considered less successful in the latter period of her reign, in her failure to secure her legacy and the exacebation of social degeneration."