It has been over 4 months since the result of the UK referendum on 'Brexit' was announced. For many EU citizens living in the UK their status and future are still unknown and feelings of uncertainty and fear linger greatly.

Sweeping generalisations and grand statements about immigration, migrant workers, and a post-Brexit utopia, churned out daily by the Leave campaign in the lead up to the vote, have now fallen silent.

Many of those responsible for such statements have gone, not only leaving it to others to sort out the resultant chaos, but also leaving those most affected by the Brexit vote in an state of uncertainty and insecurity, with little to no reassurance from government as to their future.

The ongoing anti-migration debate is one that is making our estimated 3 million plus EU-born UK residents very anxious.

While London Mayor, Sadiq Khan has addressed the 1 million European citizens living in London, thanking them for their contributions to society and affirming that they are much welcomed, little reassurance has come from central government, the Prime Minister or key parliamentary figures such as the Home Secretary.

The Home Secretary was asked to clarify the legal status of EU nationals residing in the United Kingdom as matter of priority. But no reassurance has been provided.

The Minister for Immigration emphasised that people can be confident that there will be no immediate change in their status. But such a response is wholly inadequate and leaves the lives and futures of many people in our communities, their children and their families in limbo.

We receive regular calls from concerned EU citizens who live and work in the UK, hoping to receive some reassurance that they are safe. They want to know that they and their families will not be arbitrarily sent away and the lives they have built in the UK, will not be torn apart.

A group of MPs and supporters wrote in The Sunday Telegraph arguing that it is the duty of the government to state clearly and unequivocally that any EU citizen here will maintain and continue to enjoy the rights they have acquired.

We believe this 'right' is not merely a statement of what is required morally or politically, but is in fact a right which is invested in many EU citizens living in the UK as a result of international law.

The UK is party to the Vienna Convention on the Law of Treaties that came into force in 1980. The Convention sets out the law surrounding treaties concluded between states. This includes the treaties forming the EU (which confer rights on nationals of EU Member States and others).

EU law (and domestic law to the extent necessary to give proper effect to EU Law) must be interpreted and applied in accordance with the Vienna Convention.

The Convention's protection of ‘vested rights’ may offer some protection to EU migrants. Article 70.1(b) Vienna Convention states that unless the treaty in question otherwise provides, or the parties to the treaty otherwise agree, the termination of a treaty ‘does not affect any right, obligation or legal situation of the parties created through the execution of the treaty prior to its termination.’

Under the Convention, the legal situation of the parties to the Convention (including the position of nationals of those parties) can therefore only be altered by express agreement between the parties or where, in effect, transitional provisions in the Treaty on the Functioning of the EU ("TFEU") (or one of the EU's other foundational treaties) so provide.

Our view is that once an individual, who came to live and work in the UK legally by exercising their right under the EU Freedom of Movement, has been here for 5 years (and therefore has acquired permanent residence), this right has become vested for purposes of Article 70 of the Vienna Convention.

In our view, neither Article 50 TFEU nor any other EU treaty provision mandates the removal of that right. It can therefore only be removed by agreement between all EU Member States in Article 50 negotiations.

In the absence of such agreement, stripping EU Migrants entitled to permanent residence of their rights would contravene the Vienna Convention on the Law of Treaties (and would conflict with the UK's obligations under EU Law which must be interpreted in accordance with the VCLT).

In the event that EU Migrants faced removal from the UK in contravention of any of the above requirements, such removal could be challenged by way of judicial review.