Poundworld has claimed there is “no magic formula” behind its bumper 42% increase in full-year sales to £132.9m.

The budget retail giant, whose pre-tax profits also rose by a staggering 400% to £5.2m in the year to March, according to figures at Companies House, attributed the impressive results to sheer hard work.

The company has significantly expanded over the past year, opening 29 new stores. It has invested heavily in infrastructure and in March moved to a new, purpose-built HQ, warehouse and distribution facility, which consolidated three former warehouses into one so that everything operated under one roof.

Poundworld has also rolled out a chain of new multi-price shops under the brand name Discount UK in a bid to fill the gap left by the demise of Woolworths. Ten stores have opened across the UK since October 2010 and there are plans to reach 20 by the end of the year, almost doubling the original target of 12.

“There’s been no magic formula,” said a spokesman. “We’ve worked 24/7 to deliver fantastic value everyday with general improvements to the shop floor, PoS, merchandising and overall appearance. We’ve increased the range and are working with the bigger brands such as Cadbury. We’re working with UK brands and developing product ranges and the same goes for factories in the Far East.”

The discounter, which appeared on Channel 4’s Undercover Boss two weeks ago, also plans to invest almost £500,000 in employee benefits in light of staff feedback gleaned from the programme.