This either looks like a bogus job offer or the company - as most employers do at the present economical situation - only employ those who have the right to live and work in the UK (EU/EEA citizen).
Only jobs which are on the shortage occupation list may be filled by a non-EU applicant provided there was no UK/EU/EEA citizen available to fill the gap.
In order to become licenced work sponsors companies would need a licence from the UK Home Office (£1500) and would need to pay a fee of £156 to issue Certificate of Sponsorship for work. Most companies presently just do not issue COS at present since they can easily fill their gaps with the local workforce or the EU/EEA workforce. At present there are more than 24.5 million people unemployed in the EU!