That website passes quite a few of the usual tests but not all of them.
For example, there's a postal address for returns (which is a legal requirement for UK online traders), together with a landline phone number corresponding to the geographic address.
The website says that the Steel City Lighting is actually a trading name of E L Ltd, which the Companies House website says has been in existence since 2006. The registered office of that company is at Unit 2 Clarence Works, Effingham Road, Sheffield, South Yorkshire, S4 7YS. That address, however, is simply that of a firm [CBS (Sheffield) Ltd] that sets up limited companies and provides (among other things) a postal address for them.
Google Street View shows that the
trading address (given on the website) is just a private residence on a housing estate. Interestingly, it's not the address of the couple (Cheryl & Erik Meekel) who are the directors of E L Ltd.
The firm's domain name was first registered 7 years ago, which is reassuring. However only bona fide 'non-trading individuals' are permitted to register as such (allowing them to hide their address on the Nominet website), so it's odd that the domain name is theoretically allocated to a 'non-trading' website:
http://www.nominet.uk/whois/?query=scldirect.co.uk#whois-results