Tycoon brothers present rival to Gherkin ... it’s the Cucumber

Billionaire brothers Simon and David Reuben have unveiled plans for a new skyscraper, nicknamed "the Cucumber", which is set to rival the 591ft-high Gherkin as a landmark on London's skyline.

The property tycoons, whose empire also includes Millbank Tower, want to build the 460ft glass tower on their Paddington Basin site. It will be the capital's 17th-tallest building if revised plans are approved.

The 41-storey block, officially to be named 1 Merchant Square, will include 222 flats, a 90-room boutique hotel and a public roof bar. An earlier scheme featuring more than 500 flats has been scaled down in an area where planning permission has traditionally been difficult to obtain for skyscrapers.

The Reubens, who already have permission for three Lord Foster-designed towers opposite Tate Britain, have ambitions to make Paddington Basin the Canary Wharf of west London.

The formerly derelict area has been transformed in recent years with new residential and office space. Marks & Spencer and Vodafone are among firms to relocate headquarters there.

If Westminster planners approve, the Cucumber, a joint venture, could be completed by 2016.

The plans were unveiled as it was revealed the Iraqi-born Reubens are snapping at the Duke of Westminster's heels on the property rich list.

Their fortune, assessed by expert Dr Philip Beresford for the annual list in Estates Gazette, has risen from £3.3 billion last year to £5.4 billion now.

The Duke, who has topped the list for many years, has also seen the value of his Grosvenor Estate rise — but by a far smaller margin, from £6.5 billion to £6.8 billion.

The Reubens' upward valuation is based on their data-centre company, Global Switch, thought to be worth £2.75 billion. The Jewish brothers also own part of Wellington Pubs and racecourses operator Arena Leisure.