I am 38 and have had a career in science since graduating in 1990, first as an industrial microbiologist, then I did a PhD and now work in research in academia (part-time for the past five years).

When I graduate from the PGCE I will be 39. Will I be considered too old for anyone to want to appoint me as a new teacher?

A About a third of new teachers are over 30 when they start teaching. It is undeniably clear that those who are older when they train run a risk in what is becoming a more competitive job market as additional teachers are trained and school rolls start to decline.

Unfortunately, the market takes no account of whether candidates can only apply for schools in specific locations or could relocate easily to anywhere in the country. Thus, someone who has an employment history and might want to start above M1 (pound;19,641 outside London) on the pay scale would be more expensive than a younger newly qualified teacher who would only expect M1.

The trick is to show that you offer extra value that is worth the additional money to the school. The article showed you some of the issues.

Being prepared to teach general science is a big help, as most science posts are advertised as such. Relatively few schools advertise biology, chemistry or physics posts.

There is also the issue of how you perform as a teacher apart from your subject knowledge.

This is the reason some candidates cannot find posts, even in subjects that are apparently having recruitment issues. You should ask the tutors of the PGCE course for their employment record for older students.

However, I cannot disguise that there are always risks in changing careers: even in shortage subjects

* John Howson is a recruitment analyst and visiting professor of education at Oxford Brookes University.

To ask him a question, email him at askjohnhowson@tes.co.uk