Stuart Fletcher has seen a marked change since he became a teacher 25 years ago.
Mr Fletcher, the curriculum co-ordinator for English at the Peckham academy in south London, said: "In the 1980s, most English O-levels were assessed through 100 per cent coursework.
"The focus was very much on teaching the emotional effect of the writing rather than author's craft, as it is now.
"There was also a lack of focus on grammar, which had a disempowering effect on pupils."
He is not surprised the standard of pupils' written English has improved and believes it is down mainly to the introduction of the literacy hour in primary schools and the national literacy strategy. "Both have had a big impact," Mr Fletcher said.
He believes that over the past decade, alongside a stronger focus on grammar, pupils have been encouraged to examine more closely the mechanics of writing.
"Now we look at texts with a much sharper focus. There is a greater emphasis on looking at what the purpose of the writing is and who the audience is, as well as a closer examination of the language used.
"Understanding the author's message is given a much greater emphasis, as is how the author creates dramatic effects. The pupils are then encouraged to put what they have learned into their own writing."
But Mr Fletcher has not noticed a decline in spelling standards nor a greater use of colloquial English.
"We look at the use of formal and informal language, but pupils tend to understand when to use each form," he said.
"I think the demands of GCSEs are more difficult than O-Levels, with students expected to look at, and understand, a much wider range of written materials. The standard of English has been stepped up over the past 10 years."