Consumer watchdog Which has highlighted widely varying standards in high street bra fitting services.

In its 'Bra fitting? No it isn't' report, due out next month, less than one in three high street and specialist stores of the 70 surveyed by Which made the grade and none were deemed good enough to recommend.

Some 11 researchers aged 25-75 with a DD cup size or larger were assigned to buy an ordinary bra, but found a quarter of the fittings to be of 'appalling' standard. "Our experts suggested the volunteers would have been better picking something off a market stall," noted Which.

Some of the women were apparently sold differing products with one varying by seven sizes from 34FF to 40D. One volunteer was sold exactly the same bra in two House of Fraser branches but in sizes 34C and 34F, while despite the differences in age and requirements, the 30 and 75-year old researchers were sold the same Wonderbra-style bras in La Senza that did not fit either one.

The Which criteria for proper fitting cited the need for a firm but comfortable underband, correctly-fitting cups and wire, as well as correctly adjusted straps, so the weight of the breasts is lifted off the rib-cage and shoulders and on to the lower back

Wires should also fit around the root of the breasts rather than cutting across the delicate tissue. 'Badly fitted bras don't just look awful - they can also cause neck, shoulder and back ache and poor posture,' said the report.

"Whatever their bra size, women want to look good and feel good," said Which spokeswoman, Jenny Driscoll "Heading to the high street for a fitting might seem like a simple solution, but the results we found were shocking - one bra was so poorly fitted there was room for a pair of socks in the cups.

"If stores are going to offer this service to customers they need to up their game - do it properly or don't do it at all."

Both John Lewis and Bravissimo received the best overall scores, but Which still declined to recommend them. Other shops visited included Marks & Spencer and Debenhams, but overall only 29% of the bras sold to the Which volunteers were rated as a fit.

Although the report focused on larger bra sizes, two researchers with smaller busts also reported equally poor results.

Consultant bra technologist Gillian Spencer and lecturer and technical designer Laura Savery assessed the fit of bras sold to the researchers, with David Morris - principal lecturer in contour design at De Montford University - also on the panel.