You know you’ve been at a school for a long time when an A-level student casually informs you that you used to teach his father. This happened to me recently, just after I had introduced my raffish, dynamic and deluded self to a new class.

I responded with a display of joy and gratitude - I explained that it was an honour to be dishing up the key principles of economics to another generation of the Jones dynasty. Inside, I rather wished the student had kept the revelation to himself. It was confirmation that I had achieved that dubious honour of becoming “part of the furniture”.

So is it good for a school to have staff slowly turning into furniture? I think so. But much depends on the degree of care shown to those period pieces over the years by the various people in charge. If teachers have always felt valued, they will generally age well and will be ready and willing to adapt to the ever-changing educational decor. They will also become the school’s deep wardrobes of wisdom, bursting with anecdotal history. Seeing their names on the staff list serves to reassure colleagues, children and parents alike; they become solid, enduring figures throughout students’ time at school.

But if the stalwarts of the staffroom are treated badly, you start to hear that hideous term “dead wood”. This is merely an excuse for years of rotten management of (often highly talented) staff. A consistently well-led school should be proactive enough to avoid such decay.

So how do you nurture, appreciate and utilise those older members of staff for the good of the school? And what benefits can they bring?

The value of the `legend’

Every school has at least one example of the deep and lasting impact of a long-stay legend. I often think of a former head of sixth form. When I first arrived, he somehow seemed to “be” the school. Now, 10 years after he left this world, many of us still can’t walk down certain corridors without thinking of him swishing rapidly past us. He might be in pursuit of a Lothario wicketkeeper for an imminent cricket match. Or on his way to swoop down on the smoking club. Or looking for another lost pile of essays.

Because of his deep involvement in the school’s academic, sporting and general life, this teacher came to personify it. He offered immense enthusiasm, warmth and good humour towards everyone and everything. We have humbly tried to maintain that. When he died, it seemed as if the entire town came to church for his funeral service, with hundreds more standing in the rain outside.

The need to rejuvenate

Sometimes, however, the elders need a fresh challenge. Two such colleagues seemed, at one stage, to be losing their purpose and drive. One of them was given the opportunity to lead a proposed link with a secondary school in Gambia. This involved taking 40 children for a visit each year and organising various fundraising events to support the African school. The other experienced colleague soon joined the project. Both of them found it so deeply rewarding that it revived their final few years of teaching.

Longevity isn’t everything

Even though I’m a seasoned staffroom pro, occasionally I’m not quite sure I’m up to it. We should be careful not to overestimate the value of longevity. Don’t go easy on a teacher purely because they have been around for a long time.

Teamwork is crucial

I am not suggesting that long-stay teachers are preferable to the short-stay variety. I have known dozens of former colleagues who came and went within minutes (relatively speaking) yet lit up many a young life during their time here. The most vital thing is to ensure that each department works as a closely knit team, with the rather clichd “blend of youth and experience”. That way, the best ideas will spread from school to school. Teaching across the land will advance all the more rapidly if the brilliant young nomads and old stagers of teaching are working closely and taking the very best from each other.

Stephen Petty is head of humanities at Lord Williams’ School in Thame, Oxfordshire