The UK Supreme Court is in Parliament Square in the old Middlesex Guildhall
The House of Lords will be replaced as the highest court in the land when the doors open for business at the UK's first separate Supreme Court in October.
As the Law Lords ruled on Thursday that there must be a clarification of the law on assisted suicide, following a legal challenge by multiple sclerosis sufferer Debbie Purdy, they were handing down their final judgements from the House of Lords.
At the same time, an ancient constitutional anomaly was coming to an end.
In most other democracies the judiciary is separate from the legislature - the people who assess whether laws are being properly applied are different from those who write them.
But in Britain the House of Lords - a legislative body - has also been the nation's highest court: the supreme court of appeal for the whole of the UK in civil cases and for England, Wales and Northern Ireland in criminal cases.
For hundreds of years appeals heard in the House of Lords were presided over by peers who may not even have been lawyers, let alone judges.
This changed with a major shake-up of the court structure in the mid-1870s.
Since then, the judicial work of the House has only been done by professional judges "ennobled" so that they may sit in the House of Lords - the 12 Law Lords.
They became the equivalent of other countries' Supreme Court judges.
The Law Lords are appointed by the Queen on the advice of the prime minister, usually from the ranks of the senior Appeal Court judges in each part of the UK.
In future justices of the UK Supreme Court will be appointed by the Queen on the recommendation of the Judicial Appointments Commission.
The Law Lords work full-time on judicial business. Although they are full members of the House and may speak and vote on all business, they rarely do so.
And they cannot sit on an appeal if they have previously expressed an opinion that is relevant to the case.
Once retired, they remain members of the House and can participate much more freely in debates on legislation and public policy - several do so.
However, in effect their role has been as Supreme Court judges that sit among politicians.
But from October, as a result of the Constitutional Reform Act 2005, the UK will for the first time have a separate Supreme Court.
When the new UK Supreme Court opens the Law Lords will become its first justices.
In short, the act provides for the separation of the Supreme Court from Parliament and from government.
The gradual, centuries-old separation of constitutional powers within the UK will finally be complete.