Exchange-traded funds focused on gilts have attracted interest recently as worries about the Greek debt crisis and its effect on the eurozone prompted some investors to seek safety in UK government bonds.

"ETFs/ETPs providing government bond exposure to the U.K. have been a popular choice," says Deborah Fuhr, managing partner of researcher ETFGI LLP, whose latest data show that $856 million has flowed into such investments so far this year. Among the funds attracting interest is the £1.27 billion ($1.98 billion) iShares Core UK Gilts UCITS ETF.