Amassing £20million by the time you’re 21 may sound like a passport to a life untainted by strain and strife. But Harry Potter star Rupert Grint may beg to differ – even though, at 35, his fortune has reportedly swollen to well over £40million.

Afflicted by kidney stones two years ago – eventually neutralised by laser blasts and the insertion of a stent in a very tender place – he’s also developed what he describes as a ‘huge fear’ of bees, which is quite a problem, given that bee-keeping is one of his hobbies. And now, I can disclose, his plans for Kimpton Grange, the 18th century Hertfordshire pile he snapped up for £5.4million back in 2009 but which he’s never lived in, have been deluged with derision – by the local Flood Authority.

In a scathing appraisal, it says that Grint’s proposals are ‘likely to increase flood risk’, adds that three ‘infiltration’ tests were not completed, and points out that he failed to provide ‘sufficient information’ about ‘watercourses that could be utilised for the discharge of surface water’.

Harry Potter star Rupert Grint’s fortune has reportedly swollen to well over £40 million

Plans for Kimpton Grange, the 18th-century Hertfordshire pile he snapped up for £5.4 million in 2009 but which he’s never lived in, have been deluged with derision — by the local Flood Authority

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The Flood Authority says, objecting to the plan, that he hasn’t provided ‘any information’ about the possibility of ‘connecting to a surface water sewer or a highway drain’

But that’s just for starters. Grint, who has a three-year-old daughter with girlfriend Georgia Groome, has bold plans for the 23-acre site, which includes a lake, walled and landscaped gardens, a staff flat, two cottages, an outdoor pool with its own pavilion, a floodlit tennis court and a variety of outbuildings.

Grint envisages converting a single house, The Lodge, into six flats, and additionally building four terraced dwellings and five detached ones.

The trouble is, says the Flood Authority, objecting to the plan, that he hasn’t provided ‘any information’ about the possibility of ‘connecting to a surface water sewer or a highway drain’ or about why ‘rainwater re-use’ goes unmentioned. ‘Connections to foul sewer are normally not agreed in principle,’ adds the authority, explaining that exceptions can be made only when ‘no other method of drainage’ is possible and when it will ‘not increase flooding elsewhere’.

JK Rowling has had vehement disagreements with Grint – and his co-stars, Daniel Radcliffe and Emma Watson. But perhaps she endorses something he said last year. ‘It can be cathartic,’ he reflected, ‘watching terrible things happen to other people’.