Thanks Nautilia. Have in fact purchased a 16kg. Lewmar Delta from a discount outlet. £150 delivered to the door seemed a good deal. There is a perceived hierarchy in anchors that is reflected in price and advice is varied but the Delta is hopefully an upgrade to an elderly CQR of dubious origin and it fits well on the rollers and under the bow platform. I guess a Rocna might be a further improvement. Thanks again for your input.