We filled the pond with tapwater. That's not as bad as it sounds because we're not on the mains - we have our own well. So the water isn't chlorinated. (And, thanks to testing, we know it's not full of nitrates, either.)

As the level imperceptably rose, we made a last-minute decision to extend the pond. On one side, we dug away the turf and topsoil in a 'D' shape. Fortunately, we'd bought an oversize liner, so it was able to stretch to cover this. Along the edge of this shallow area, we placed a row of faced granite stones: we have lots of these as our property once had several additional buildings, now ruins, so the land is littered with mediaeval building rubble. The line of stones is there to hold back soil which we piled into this shallow region, and this has now become our marsh area.

A shallow marsh area is good for many reasons. It broadens the range of plants you can use in the pond. And it's one of the richest environments for wildlife.

The whole point of this pond is to encourage wildlife and biodiversity (which is why we've got a 'strictly no fish' policy). So we want to create as many different habitats as possible.

It took around eight hours of running the hose to fill the pond (during which time we had no water available in the house). When it was near-full, we started to edge it. Along two sections we placed railway sleepers which will eventually form the bases for two areas of decking. Along other sections we placed more granite stones (protecting the liner with corrugated card). We brought the liner up behind the first row of stones and held it in place with a second row. This has raised the waterline slightly above the surrounding ground.

The only place we didn't do that immediately was where we'd created the marsh area. Because of the spoil heap, the ground there was higher anyway. So we made the decision that the spoil heap would become a raised bed.

Leaving aside the digging of the hole, the process of lining, filling and edging the pond took a weekend. At this point there was still a lot to do - but we had a pond, after all these years of waiting.

It didn't take the wildlife long to find it, either. We had waterboatmen, pond skaters, grooved diving beetles and dragonflies - southern hawker, red-bodied darter and broad-bodied chaser (or possibly keeled skimmer) - within 24 hours. The southern hawker used the mossy granite to lay eggs. And droppings on the stones tell us that the birds are coming to drink.

The cats (including Rockwell, above) are convinced there should be fish in the pond. We haven't the heart to tell them there never will be any.

Even in its untidy state, we were amazed how much difference the pond made, with its reflections of the sky. It's like turning on a light in that section of the garden. (In the picture above, the section on the right is the marsh area).

It's also great to see water glimpsed from other areas on the garden. Below, for example, it's seen through what will soon become the bamboo grove (that's Pseudosasa japonica on the left).

There's still a lot to do, but all-in-all, not a bad weekend's work.

Our new pond has no natural water supply - no source or stream to feed it. We always knew we were going to have to fill it (and occasionally top it up) from the tap. It's important, then, that it holds water as well as possible.

Having dug into clay, we did momentarily entertain dreams of simply puddling the clay and allowing the pond to fill naturally.

Fat chance.

We puddled the deepest bit and turned on the hose to see how long the water would remain. Not long, was the answer. So it was off to the Interwebs to check out liners.

The standard solution these days is EPDM butyl. To fill a hole 6.5m long and 4m wide, with the required overlap at the edges, we calculated the cost from French vendors at about €550-600. But then Trish discovered the Flexiliner product from Pondkeeper.co.uk. This is thinner than standard butyl liners (read, easier to manage) but has similar UV resistance. And, even with geotextile underlay, it was about half the price. They offered very reasonable delivery rates to France, too. In three days from ordering, our new pond arrived in the post.

Before we could play with the liner, though, we had some more preparatory work to do.

The biggest danger with liners is making holes in them. And the most common culprit is a stone underneath the liner.

Water is heavy. The deepest part of our pond covers an area of, say, 4 square metres. With a depth of about a metre, that's 4 tonnes of water pressing down on the liner.

So, first you scour the floor and sides of the pond, pulling out any stones you find. We were pretty lucky in having largely stone-free soil. Then you add a layer of protection.

A common solution is to put down a layer of sand. We didn't like that idea much because of the difficulty of getting sand to the location. An alternative is to put down old carpet, or thick layers of newspaper or card. Or you can buy underlay.

We opted for a belt & braces approach. Friends gave us old sections of carpet and where that didn't cover we laid corrugated cardboard. The result was, somehow, very poor white trash. It also had the effect of making the pond look surprisingly small.

Then we laid the geotextlie. This comes in 2m wide strips and is very similar to the stuff gardeners use to supress weeds in flower beds or around new shrubs. It's soft but very tough and should help to discourage roots and moles as well as protecting from stones.

Once all the underlay was in, the pond started looking large again. The photo below shows it before we began working on the wrinkles.

Next came the liner itself. We were lucky in having enough space to fully unfold it and lay it flat before moving it into position. We then eased it down into the hole, gently prodding it into the curves of the pond with a broom. Once it was in place and the worst of the wrinkles removed, we added back about 5cm of topsoil (checking carefully for stones). Then we started to fill the deep section with water so that the weight of it would pull the liner into position.

Once the water neared the top of the deep section, we turned our attention to the shallower areas. One end of the pond has a relatively large shallow area and we thought that this is where Zola, our spaniel, is most likely to jump in. So we covered the liner with more geotextile and a couple of old doormats. Then we covered most of the shallow sections with soil.

As the water level rose, we made a sudden, last-minute decision to extend the pond, but more of that in the next part... 

The key element that's been missing from the garden is water. Or, it was.

Trish has been hankering after a pond for years. We always knew where it should go: the Japanese garden is the lowest point on our land and is where the slope of the hill flattens out for a while. If a natural pond had ever formed, it would have been here.

We also knew that, below about 20cm of rich loam (thanks to this land being used for centuries' as orchard) there is dense clay. We wondered if we might get away with simply puddling the clay and not using a liner.

The tricky bit was always going to be digging the hole. Then we got lucky. We were able to trade our old wood-burning stove for some mini-digger time. After years of waiting, we could finally have our pond.

The day before the digger was due to arrive, we marked out the shape we wanted. (Well, okay, it was the shape I wanted: Trish kept saying "bigger!".) Having scraped the shape in the grass, we made it clearer by digging a small trench - easy in the friable, drought-ridden soil.

Our friend Gruff arrived with his neighbour Paul the next day. It's always a pleasure watching a craftsman at work and so it was with Paul who wielded the mini-digger the way a cabinetmaker uses a chisel.

We dug the main area of the pond to a depth of 45cm, then a deeper central portion to the same again, making it 90cm deep. As the soil came out of the ground, I kept an eye open for any archaeological finds (yes, I'm a Time Team geek). We found many pieces of a crude, orange tile. In fact, we find this all over the garden in spite of it not being used on any of the remaining buildings. There were also parts of a blueish-grey pot.

Paul, it turned out, is also a Time Team fan, metal detectorist and a keen amateur archaeologist. He told us that, as a digger operator, he's made thousands of holes in Northern France and come up with very few finds. When he worked alongside arachaeologists in the UK, every hole seemed to yield interesting pieces. Maybe it has something to do with population density or the highly agrarian nature of this region of Normandy.

In no time we had an impressive hole and a massive spoil heap (or 'anti-pond' as I like to think of it). Once the boys had left, we tidied up the hole, chamfering the edges somewhat, and then thought about what we needed to do next.