Media playback is unsupported on your device Media caption The artist, Cecil Balmond, says the Star of Caledonia could represent a thistle or saltire

Hmm, how to describe it? A pin cushion? A nail bomb in mid-explosion? A starburst? A thistle maybe? Maybe. Or - and I think this might be the one - a hedgehog caught in a net? Whatever, it's difficult: trying to work out just what it is that is depicted with Scotland's proposed new landmark.

The spiky beastie does have one very clear point. And that is to be big. It will be at least 55m (180ft) high and 40m (131ft) across. Once built it will be placed in a field alongside the bridge where the M6 motorway turns into the M74 and England turns into Scotland. It is intended as an iconic welcome.

The current welcome is almost ironic - in that there barely is one. Driving between Scotland and England at the moment is like playing tennis without any court markings; you never quite know when you are in and when you are out.

The X of the Scottish Saltire that marks the spot is a modest road sign easily missed because a) it's quite small and you are going quite fast b) you're gaming, sleeping / tuning the radio and possibly driving too or c) it has been obscured by one of the other five million vehicles that go up and down that stretch of road every year.

And that won't do. The good folk of Dumfries and Galloway say they want to give people driving across the border (the landmark is primarily intended for cars travelling south to north) a hearty welcome to Scotland. And what better way to do that than produce a giant piece of eye-catching, attention-grabbing, in-yer-face public art: a slug of visual Red Bull for the weary driver.

They've seen what the Angel of the North has done for the North of England. They've seen how its enormous arms have gathered tourists from hundreds of miles into the warm bosom of Gateshead. And they've seen that once there, how those tourists have spent their cash on everything and anything. And they've thought: we'll have a bit of that.

According to the notes provided by the Gretna Landmark Trust (the group behind the new landmark) Anthony Gormley's Angel of the North "paid for itself within a month." In terms of global marketing that is. Which is what the new landmark at Gretna is really about: more honey pot than "hello honey".

You know why Grenta Green is famous. Three-quarters of a million people rock up there every year, many with marriage on their mind. It is a Caledonian Vegas. The town has the only high street I've ever walked along where there are more flower shops than estate agents. Watching the ant-like stream of soon-to-be or newly-weds march in and out the The Blacksmiths Shop is like taking a short course in anthropology.

The proposed landmark would be a new photo-op for the snappy couples, while giving the town a chance to be famous for something other than nuptials. It is a branding exercise for the area as well as for Scotland.

It is art and propaganda. Like Tatlin's eponymous Tower (1919-21), which the Russian Constructivist designed to be the HQ for global communism, this new structure is an artistic creation that wants to support and please the state.

It's the work of a dapper American and an ambitious Sri Lankan. Charles Jencks is a land artist who moved from America to Dumfries and Galloway, who is now a "key part of the region" says the blurb. He is responsible for the landmark's swirling, earth plinth.

Cecil Balmomd is a revered engineer who has helped produce some of Anish Kapoor's monumental pieces. He now wants to "do a Brian Eno" - and become an artist. It is his spiky metal design.

Balmond describes the proposed landmark (working title: Star of Caledonia) as a "contemporary symbol of a confident, creative Scotland". Designed to communicate "Scotland's power of invention". In these days of devolvement it is a chance to assert Scottish National identity: a reading of the house rules before you enter.

The designers say the structure communicates the energy, modernity and inventiveness of the Scots. It's a long way from the identity Sir Walter Scott is held responsible for creating: that of a Romantic nation, full of industrious people who wear tartan and stare out meaningfully at their picturesque landscape.

It is also long way from being built. The proposal has not yet been given planning permission or the £3m needed to realise the vision. It could end up like Tatlin's Tower and never be built. That's beginning to look like it might be the case with Mark Wallinger's White Horse proposal for Ebbsfleet in Kent.

The idea is to have the Gretna Landmark ready for the Glasgow Commonwealth Games in 2014. I hope they make it. I do like a staging post or something to spot on a long journey. And I'd enjoy the inevitable conversation with any fellow passengers. Is it a contemporary folly? Should they have spent the money on a youth centre (as one local told me) in Gretna? What's Scottish about it? What's the point of it? And stuff.

And after we have talked that through, we could then all agree that it is a lot better than all those smurf-like creatures that pop-up along the roadside when drive through France.