To keep fit, first buy some trainers... What next from Pippa Middleton?

Does Pippa Middleton have another book waiting in the wings? In last week’s Spectator she joked that she should follow up her party planning guide Celebrate with a cookery book that would include tips on how to make an omelette — “you have to break at least one egg” — or perhaps with a sequel called Bottoms Up — “now that could be a bestseller”.

But was she being more serious than she sounded? The Londoner has learned that the Duchess of Cambridge’s multi-talented sister originally planned to release a whole series of useful guides. As well as her invaluable party tips, Pippa has previously discussed writing a keep-fit manual, based on her extensive sporting prowess.

A keen athlete from a young age, Pippa won a sports scholarship to Marlborough, and continued to enjoy hockey, tennis and daily workouts while at university in Edinburgh. Recently she has clocked up an admirable number of charity runs, battling through Blenheim Palace’s 5km triathlon, the 80km Highland Cross endurance race in Scotland and Sweden’s 56-mile Vasaloppet cross-country ski race — despite having never done any cross-country skiing before.

Celebrate was published by Penguin in a deal thought to have been worth about £400,000. A random Penguiner mentioned to the Londoner that Middleton’s representatives approached the publishing house with the idea for the second book but, given the not entirely glowing reception given to Celebrate, it politely declined to get its cheque book out again.

But could they have missed a trick? With such an impressive range of sporting achievements under her belt — combined with her famously toned physique — a keep-fit guide from the future Queen’s sister might actually make it to the bestseller list.