Andrew Mountbatten-Windsor's grace-and-favour mansion on the Windsor Estate was not inspected by officials once in the 22 years he lived there rent-free, the Daily Mail can reveal.

When the lease for the 30-room Royal Lodge estate was signed in 2003, it included unique terms which included no rent but a costly upfront refurbishment and upkeep schedule.

The disgraced royal paid £8million to repair the then-dilapidated property, and promised to allow inspectors in at 'all reasonable times' to make sure he looked after it.

In return his Crown Estate landlord, the independent company which manages Crown properties for the benefit of the taxpayer, allowed him to pay no rent for the duration of the 75-year lease.

But the Mail can now reveal that not one Crown Estate official carried out an inspection of Royal Lodge in the whole time Andrew lived there – raising concerns of a 'sweetheart deal' at taxpayers' expense.

His lease states that he must paint the interior of the property every seven years and maintain the landscaped grounds and gardens in good order.

The rules were so strict that he was also not allowed to alter the historic building by adding new walls, fences, gates or windows.

To ensure compliance, the lease states Crown Estate officials had the right to enter the premises to ascertain if the rules had been followed if they gave 'reasonable notice'.

A recent photograph of Royal Lodge clearly shows it's state of disrepair with plaster peeling off the exterior walls

Andrew's lease states that he must paint the interior of the property every seven years and maintain the landscaped grounds and gardens in good order

The disgraced royal paid £8million to repair the then-dilapidated property when he moved in, and promised to allow inspectors in at 'all reasonable times' to make sure he looked after it

But the revelation that no visits were ever paid will raise further questions about whether courtiers attempted to play down concerns over the former prince's value for money as outrage grew over his links to paedophile Jeffrey Epstein.

The lack of inspections was only revealed via a freedom of information request from this newspaper in December.

This is despite the chief executive of the Crown Estate writing a briefing to the House of Commons Public Accounts Committee (PAC) in November where he stated inspections were carried out on a 'need-only' basis.

It stated that this was 'common industry practice' because Andrew had the right to the quiet use and enjoyment of the property, and the landlord's reversion was several decades away.

It explained inspections are carried out only when needed to ensure best use of resources and, in the case of The Crown Estate, 'effective use of public money'.

Royal expert Richard Fitzwilliams said: 'There is little doubt that the extraordinary absence of inspections of Royal Lodge, which under the terms of the lease could be periodically carried out, will be seen as yet another example of the sweetheart deal between the Crown Estate and Andrew.