ASOS say the Duchess's new dress is so popular, they're planning to expand the range to other colours too

Kate Middleton has proved her Discount Duchess‘ status once more.

Not only has Prince William’s gorgeous wife been spotted out and about in a dotty Topshop dress, she’s splashed just £17 on an ASOS.com maternity frock.

Kate was snapped shopping for nursery furnishings last week at Chelsea interiors store Bernard Thorp in the navy bargain buy, adding her trusty £80 Pied a Terre wedges and a berry-coloured cardigan. 

Available in sizes 6-18, the ASOS Maternity Belted Dress With Scoop Neck – reduced from £25 – features a practical elasticated waistband and tie-detailing to accommodate Kate‘s ever-growing Royal Baby Bump.

Best of all, it proves the Duchess is putting her feet up and shopping online like the rest of us!

The dress, which comes in navy, orange and cream, has proved so popular that ASOS have announced that it’s looking to expand the range to other colours.

Kate Middleton‘s maternity dress is still available, but hurry, before the Kate Effect truly kicks in!

SEE PICTURES Kate Middleton‘s Style File 

SEE PICTURES Prince William and pregnant Kate Middleton enjoy Harry Potter set visit

SEE PICTURES Pregnant Kate Middleton dresses baby bump in hot red Armani coat in Scotland with Prince William