WINCHESTER Cathedral is subject to a deceptive optical illusion.

It appears to be one of the smallest of medieval English cathedrals but it is in fact one of the biggest.

There is no official ranking of cathedral sizes but, in sheer length, our cathedral is very big indeed.

It is the longest medieval cathedral in the world.

The nave is the main section of a church, and the nave of Winchester Cathedral is not only the longest but also among the tallest in England. Only the naves of  Salisbury, Ely and Lincoln cathedrals are taller.

So, if it is among the giants, why does our cathedral look rather small? How the great church deceives the eye is something I have pondered for years. Next time you gaze upon the world-famous building, you might like to consider whether you agree with my conclusions that the visual shrinking is down to five main factors.

READ MORE: Popham Airfield: More than 400 objections to major development plans

The first factor is simple. Our cathedral doesn’t look as big as it might because it has no tower to speak of. Its apology for a tower is little more than a square stump. 

The second factor in my opinion is absence of a high platform for the cathedral to sit on.

Recognised giants Durham Cathedral and Lincoln Cathedral look even bigger than they are because they look down on you from their sites atop high ground. Having to look up to them gives an impression of immense bulk. But our cathedral sits on low ground, so visitors’ first impression is less than overwhelming. As they approach its front door from Symonds Street visitors look down on it.

The west side of most cathedrals is crucial. It influences visitors greatly because normally the west side, or elevation, is where the front door is. That is the elevation visitors see as they approach before entering. Medieval cathedrals were designed to impress so it is unfortunate that the elevation of Winchester Cathedral which impresses least is its west elevation. It looks smallest on that side, despite it featuring what is effectively a wall of glass 50 feet high.

SEE ALSO: Waterstones planning to open in Romsey's old M&Co unit

Factor Three: The main thing that stops that mighty west window and the whole west elevation looking as huge as they really are is the small size of its unusual stone porches that stick out at the bottom. So you walk not into a soaring architectural cliff about 100 feet tall but a porch only about 20 feet tall.

Intrusive out-of-proportion stone balustrades above the porches also shrink the west elevation. They are my fourth factor.

Despite the porches and the balustrades, the cathedral’s west side, or elevation, would still look reasonably beefy if it wasn’t for my fifth and final shrinker. That is the effect of three features at the top of the west elevation. These are stone pinnacles which soar above the roof and presumably were meant to make the building look taller. I think they have the opposite effect. The great height of the pinnacles – two stout ones and, highest of all, a slender central one – seems to mock the roof for not reaching as high as they do.

I have used pictures of the cathedral to test my theories. With a photograph you can put your hand over the three pinnacles and see whether, as I claim, removing them makes the west front magically look bigger.

Use your hand or a piece of paper to hide the porches and that, too, makes the west window and the whole west elevation look bigger.

Of course the size of the cathedral is just one aspect of its character. Its beauty, its history and its variety of architectural styles – brutal Norman to delicate late Gothic – make it one of the most enjoyable cathedrals in England.

Cathedrals expert Simon Jenkins puts Winchester in his top six and I remember journalist Janet Street-Porter, who trained as an architect, declaring Winchester her favourite.