Two elderly sisters are set to argue for inheritance tax exemptions which usually apply to civil partners and married couples.

The siblings have been living together in Wiltshire since they were born, but Joyce, 88, and Sybil Burden, 80, fear that one of them will be left with a large inheritance tax bill when the other passes away.

Last year’s implementation of the Civil Partnership Act brought inheritance laws for gay couples in line with those of married couples, meaning a surviving spouse will inherit their partner’s estate without paying tax.

But the law does not apply to family members living together, which Joan and Sybil claim is a contravention of their human rights.

PinkLegal.co.uk barrister Alistair Kelman said: “In fairness they have a good case, this highlights the unfairness of inheritance tax.

“The best thing to do would be to abolish the spouse and civil partnership exemption but raise inheritance tax so that it would hit the very rich.”

Their case will by heard by the European Court of Human Rights in Strasbourg today.