Air bags, stick-on cups, magic foam... how do cleavage-boosting bras compare?

By Daily Mail ReporterMarks & Spencer has launched a new bra which aims to enhance cleavage by two cup sizes.But how does it fare compared to its rivals - which include the Wonderbra, seamless bras and a 'memory foam' bra.Here we put them to the test... La Senza three-way Air Bra, £18, left: The maker claims this bra will boost you by a cup size - and give you the freedom to control the shape