A very cleverly-designed mattress offering a particularly comfortable night's sleep for people owning a caravan has been given a large chunk of cash for further development after an appearance on Dragons' Den. New dragon Hilary Devey, a packaging expert, happily invested £80,000 into the invention from husband and wife team Liz and Alan Colleran. Alongside a carefully thought-out and confident pitch, the concept of the Duvalay - a zip-up memory foam mattress and duvet - wowed Ms Devey into parting with her hard-earned cash. The product ensures that caravanners get a warm night's sleep; the side of the compact bed rests against the caravan wall and can be zipped up, meaning the backs of people who use it do not get cold. A major bonus of the use of memory foam technology also means that people will get better-quality rest, aiding with back problems, according to the creators. Of course, the idea was not without its detractors; Deborah Meaden, Peter Jones, Theo Paphitis and Duncan Bannatyne all pulled the plug on investment.