When Ken Sims bought Thrigby Hall and its sun-parched grounds euphemistically described by estate agents as 'rough shoot' in the long, hot summer of 1976, the local tourism scene was in an altogether different place to now.

Filby's noisy neighbour Great Yarmouth was veritably buzzing although he concedes the number of visitors sardined into Regent Road had still somewhat declined from his visits as a teenager in the 1950s.

Four decades on, Norfolk's leading resort has come through a journey one might compare to the rollercoaster at its famous Pleasure Beach, but one with inevitably more dips than rises.

However, as Mr Sims, 74, and his wife Beryl prepare to step back from the day to day running of Thrigby Hall, he is reassured that the resort on his doorstep still maintains a £500m-plus tourism sector.

'Thanks to the Greater Yarmouth Tourist Authority and the efforts of the borough council's tourism department, Yarmouth has been saved from the disintegration of many other resorts like Margate,' he said.

And while Yarmouth has benefited from a £20m EU-funded seafront regeneration scheme and proved it can be at the vanguard of such modern developments as online booking and digital marketing - it was even the first resort in the region to launch an app – Thrigby Hall has progressed in its own almost languid way. Having had his fingers burned in a disastrous business partnership which saw his first attempt to open a zoo in Penang end in failure after a 12-year stint as manager of a Malaysian rubber plantation, Mr Sims arrived in Norfolk with little money to invest.

He said: 'I relied on friends, family and the bank and in those days interest rates were going sky high.'

There was also local opposition to overcome, which could have sapped the will of many entrepreneurs, delaying the zoo opening until 1979.

'Our first day was on June 17. Admission was 50p for adults and we took £12,' he said.

Ten lean years not helped by high interest rates were followed by 10 in-between years but since 2000 'things have become very comfortable, very viable'.

While the record annual visitors number of 111,000 was reached in 2003, Mr Sims is content to have maintained an average of 65,000.

He said: 'Since we opened, it has become far more competitive with many other attractions opening, including the Dinosaur Park, Pleasurewood Hills, Bewilderwood and the Sealife Centre. The visitors cake is only so big.'

Mr Sims has always taken a cautious approach to investment, believing that is important in a weather dependent business with seasonal fluctuations.

However, since selling Cromer's Amazona Zoo last year, seven years after launching it to realise his dream of establishing a South American collection, there has been more money to spend at Thrigby.

He said: 'We built a new porcupine enclosure last year and a new meerkat enclosure this year.

'The children's play areas at the zoo are also getting more attention.'

Mr Sims, who has two grown-up daughters, is proud to have retained loyal, long-serving staff and has now appointed three of them as directors - alongside him and his wife - to take over responsibility for the day to day management.

Scott Bird (15 years at Thrigby) is zoo director, Carol Payne (20 years at Thrigby) is responsible for the shop and tearoom and Linda Barnes (35 years at Thrigby), who started as a YTS trainee, is head keeper.

Assured that 'the long term prospects for the wildlife gardens and the wonderful animals here will be in good hands', Mr Sims will now focus his energy on his role as a director of Yarmouth tourism business improvement district (BID).

Although the BID which levies £500,000 a year from businesses in the borough to support tourism has proved controversial, Mr Sims said he was a 'strong supporter'.

'In light of huge central and local government cutbacks the BID is the only way to ensure the resort gets the publicity and support it needs. Yarmouth without tourism is not a place to contemplate,' he said.

'Tourist authority fact-finding trips to other resorts have shown Yarmouth leads the field in many ways but the BID will help it stay ahead through professional marketing.'

He is optimistic about the prospects for domestic tourism - 'personally I am turned off by the hassles of airports' - and believes Yarmouth will be lifted greatly if Pleasure Beach boss Albert Jones is finally successful in delivering the resort's long-awaited multi-million pound large casino complex.

Have you a tourism story? Email stephen.pullinger@archant.co.uk