Well, the custom at the time was the distance covered by a cannon ball. That was the origin of the territorial waters. So some form of marking this existed as also British claim a neutral zone between the Gibraltar and Spain which was negotiated at the time (with the shooting of another cannon ball) but it was denied by the French. So the territorial waters should have been marked as the neutral zone ... and none were reflected in the treaty ... because ... the cession of Gibraltar was without territorial jurisdiction ... It is only a Property deal, not a sovereignty deal ... that's why there were no delimitation of territorial waters and neutral zone.

UK should respect the spirit and letter of the Treaty.

There are no territorial waters for Gibraltar as Gibraltar was ceded without any territorial jurisdiction and if the latter is not ceded, then the former are not granted.

An interesting and well written article ... without mention that UK is consistently and unilaterally breaching the Treaty of Utrecht.

You had a chance to provoke the Chinese over Hong Kong ... but UK ... ran away.

UK has consistently and unilaterally breached the Treaty of Utrecht. The Treaty is about the cession, never the sovereignty, of the city of Gibraltar together with other assets. The word Property appears twice and the word sovereignty none. It appears the cession of the property WITHOUT any territorial jurisdiction, hence Gibraltar is Spanish in perpetuity and a day.
Many in Gibraltar feel anxious about the outcome of the Brexit vote. After all, 96 per cent of the Gibraltarians participating in the referendum voted to remain in the EU. Never miss the point that the ones endangering Gibraltar’s future is not Spain but UK. It turns out that UK wants to enjoy the same benefits of being in the EU once UK is out. The same way in UK once you have cancelled your membership in any British golf clubs, you still can enjoy the facilities as long as you wish … without paying for that membership. Of course!!
Gibraltar unique status inside the EU should come to an end and be out the EU once UK is out as well. Let me remind you that UK is the one taking Gibraltar out of the EU, never mind Gibraltarians’ wishes, interestes and democratic exercise (96% in favour of being part of the EU).
1) Gibraltar is a Spanish territory as the territorial jurisdiction was not ceded. Gibraltarians remain wholly and completely British for as long as they want this;
2) Gibraltar is a tax haven.
3) Gibraltar will not enjoy any economic future thanks to UK that is getting her out of the EU. Any wishful thinking is welcome but it ficticious.
Spain can veto any interference of any other part about the future of Gibraltar outside the EU. The only actors are UK as the Administering Power of the colony and Spain that wants the Treaty of Utrecht respected or terminated with the return of Gibraltar to Spain.
There is no official census that13,000 Spaniards from Andalucía rely on employment in Gibraltar. The Government of Gibraltar refuses to create such census. This is always an inaccurate mantra, just a lie. The only truth is that 30,000 Gibraltarians need Spain to survive and the proof is the interest of both UK and Gibraltar to maintain the border open, other wise UK should chip in for this British population.
The anachronistic and disloyal behaviour towards the Treaty rely in UK that is breaching the spirit and letter of the mentioned Treaty by giving rights to a British population but that a third party (Spain) has to provide for. Mr Coffey acknowledges that he can invite his friends to the most expensive restaurant in town as someone else is paying for the bill. The wishes of the People of Gibraltar must be satisfied by UK at her expense and not at Spanish expense, interests and rights established in a Treaty. As Gibraltarians are not Spanish nationals, Spain has no obligations towards this British population, so Spain chooses to retain her rights established in the Treaty.

UK is not respecting the Treaty of Utrecht hence the cession must come to an end.

You may argue that this cession was "in perpetuity", which is true, but always respecting the restrictions. These restrictions/conditions are not met by UK that broke them unilaterally.

First of all, the Treaty of Utrecht states the cession of the property of some assets (the town and castle of Gibraltar, together with the port,fortifications, and forts )… nothing else and this cession is under some conditions.

FIRST CONDITION
Cession without any territorial jurisdiction.

This invalidates that any kind of sovereignty is ceded and emphasises that the cession is only about a property of the above mentioned assets. Gibraltarians are born and buried in Spanish soil to their grief. They do know this.

Gibraltar is a Spanish territory to perpetuity and a day …as the property was the only thing ceded to Great Britain WITHOUT ANY TERRITORIAL JURISDICTION hence it NEVER CEASES BEING SPANISH hence the principle of territorial integrity, as specified in resolutions 1514 (XV) applies fully. Territorial Waters and airspace are based in this territorial jurisdiction and as the Treaty clearly states this was not ceded being all the waters around Gibraltar Spanish (as Gibraltar still is!).

Gibraltar's soil is as British as the soil of the Spanish Embassy in London is ... Spanish ... because Spain can own the property of the building but the territorial jurisdiction is not ceded by UK... so ... in any Embassies in UK any births will be by default... British.

SECOND CONDITION
Without any open communication by land with the country round about.

It’s both UK and Gibraltar forcing Spain to maintain the internal border open as they both know there is no future for Gibraltar if this open communication by land didn’t exist. I have heard thousand of times that Gibraltar can live without this connection … but we know the story any time Spain needs to close it.

Once UK is out of the EU, Spain will gain full control of her borders. They can whine, beg, cry, scream as much as they like.

THIRD CONDITION
The end of the cession means Gibraltar must be integrated with the rest of Spain.

In the treaty is predicted all possible ways to return Gibraltar back to Spain (grant, sell or alienate the PROPERTY). It is very important to keep track of this noun “the property” because this Treaty is about the cession of a property, not sovereignty!!!

This condition invalidates that Gibraltarians are granted the self determination right that they all are chasing for and begging for in the UNO. All UNO Resolutions are in favour of Spain claims that proved that Gibraltar is Spanish as well as the sovereignty was not ceded. Gibraltarians are not acknowledged as the original population of Gibraltar but a planted population by UK.

UK-GIBRALTAR-SPAIN
The main breach of the Treaty.

UK is inviting Gibraltarians to rights that someone else must pay for. The wishes of the People of Gibraltar must be satisfied by UK at her expense and not at Spanish expense, interests and rights established in a Treaty. As Gibraltarians are not Spanish nationals, Spain has no obligations towards this British population, so Spain chooses to retain her rights established in the Treaty.