The two houses are intended for Miss Rowling’s two youngest children David, nine, and his sister Mackenzie, seven

The Hogwarts-style towers - estimated to cost around £150,000 – are so big that they need planning permission

When the creator of Harry Potter decides to build an adventure playground for her children, you expect something magical.

But even by JK Rowling’s standards the 40ft high, two-storey tree houses planned for the back garden of her Edinburgh mansion are something spectacular.

The Hogwarts-style towers - estimated to cost around £150,000 - are so big that they need planning permission.

Victory: Harry Potter author JK Rowling has won a battle to build two luxury tree houses in the garden of her home despite protests from local residents. This picture shows a computer simulation of the twin tree houses

Expense: The writer had applied to have the massive structures, estimated to cost £250,000, erected as part of a programme of renovations at her house in Edinburgh

Each wooden tree house is to be built on stilts and boasts balconies, carvings and turrets that wouldn’t look out of place in a Potter adventure.

The towers are linked by a rope bridge and can be approached by a secret tunnel hidden underneath a raised wooden walkway.

Plans lodged with the council reveal the houses are intended for Miss Rowling’s two youngest children David, nine, and his sister Mackenzie, seven.

Children's dream: Each wooden tree house is to be built on stilts and boasts balconies, carvings and turrets that wouldn't look out of place in a Potter adventure

Eco conscience: JK Rowling's tree houses will only be built with timber from sustainably managed forests According to the drawings ‘David’s Tree House’ is closest to the secret tunnel and has a specially designed trap door and fireman’s pole escape into the garden Meanwhile ‘Kenzie’s Tree House’ has its own spiral staircase and a stainless steel playground slide leading to a double set of swings. A wooden walkway connected to the giant structure leads to a giant trampoline deck that is shielded from public view by a row of extra tall conifers. Impressive: Hogwarts as it appears in the film Harry Potter and the Sorcerer's Stone

Intricate design: After the extraordinary plans were submitted with the council last month, objections were lodged by people who live nearby

Bespoke fun: Plans reveal the houses are intended for Miss Rowling's two youngest children David, nine, and his sister Mackenzie, seven

The design by the luxury tree house makers Blue Forest UK features cedar shingle roofs and a built in ‘nature box’ for birds to nest in.

Miss Rowling, 46, lives in her 17th century mansion with her husband Dr Neil Murray, their two young children and her 18-year-old daughter Jessica, from her first marriage

JK Rowling’s tree houses will only be built with timber from sustainably managed forests.

Miss Rowling, 46, bought her 17th century mansion for more than £2 million in 2009 when she reportedly fell in love with it after viewing just two of its 31 rooms.

She lives there with her husband, their two young children and her 18-year-old daughter Jessica, from her first marriage.

The property has been dubbed ‘Fortress Rowling’ by some because of its security fences and reinforced doors.

Giant trees were lifted by crane over the garden walls to give the author and her family more privacy.

Last year JK Rowling got planning permission to flatten a £1 million 1970s style house next door to make her garden larger.

She also got approval to build a summer house that critics said looked like the stone hut inhabited by Hagrid, the giant groundsman from her best-selling novels.

Yesterday a neighbour said: ‘Nobody around here is going to make a fuss about the tree houses for her children. It’s her cash she can do what she wants with it.

‘Miss Rowling has spent a lot of money on trees surrounding her property so even if these tree houses are huge nobody but her is going to see them. In any case she’s extremely nice and well-liked around here.’

A source at the council said: ‘It would be highly unlikely that JK Rowling will not get permission for these tree houses.

‘They are only for her children to play in, she’s not seeking permission for residential permission for them.’

JK Rowling is worth around £560 million according to the 2012 Sunday Times Rich List.

She is reported to have given away more than £100 million to charity.

Wealthy: Daniel Radcliffe is pictured as Harry Potter. Creator JK Rowling is worth around £560 million according to the 2012 Sunday Times Rich List

Blue Forest, based in Tunbridge Wells, Kent, describes itself as the UK’s leading tree house architects.

It specialises in creating ‘fantasy castles’ like those for JK Rowling’s children or ‘James Bond-style hideaways’ with luxuries such as under floor heating, wood burning stoves and plasma screen televisions.

Prices start at £20,000 for its most basic models, but the firm admits the ‘sky is the limit’ for the final bill when it creates bespoke tree houses for the super-rich.

The firm’s managing director Andy Payne said: ‘Tree houses have always been a symbol of imagination and creativity.’

Tree houses are generally considered temporary structures and therefore do not need planning permission.

However this only applies if they are less than 13 feet high from roof to base.