The outfit Prince George wore to Princess Charlotte's christening has already sold out

Prince George of Cambridge leaves the Church of St Mary Magdalene on the Sandringham Estate for the Christening of Princess Charlotte of Cambridge in King's Lynn

Is anyone really prepared to spend £85 on an outfit for a one-year-old baby who is going to grow out of it almost instantly?

Well , yes, but at least the child won't be old enough to be embarrassed when he sees his peers wearing exactly the same outfit.

Royal fans have been splashing out on the outfit worn by Prince George to his sister’s christening, with the £85 red and white smock designed by Rachel Riley selling out within 24 hours.

Despite the hefty price tag, the smocks sold out in the 12 months and 18 months sizes.

The red and white smock was an almost exact replica of an outfit worn by his own father when he made his first visit to see his younger brother Harry in hospital.

Prince William in 1984 and Prince George at Princess Charlotte's christening (Rex Features/Getty Images)

The royal toddler frequently inspires fans to flock to order replicas of his outfits for their own children. Crocs, dungarees and swaddling blankets have all previously sold out after being "endorsed" by the prince.

Last month it was revealed that the cost of the monarchy to the taxpayer rose by nearly six per cent last year; more than double the rate of inflation. Official expenditure from the Sovereign Grant, the amount released from the public purse each year to finance the monarch, increased to £35.7m - a rise of £1.9m on the previous year.