The building was valued at about £500m as recently as two years ago, according to the Sunday Times, which first reported details of the sale process.
The private equity firm Apollo will receive the first £311.6m of a sale of the property as it was Redcastle’s senior secured creditor.
Green took control of Topshop in 2002, when his investment company bought Arcadia.
Online retailer Asos bought the Topshop and Miss Selfridge brands for £330m in February, but did not buy any stores.
In 1965 Topshop took over the basement of the Oxford Street building, which started life as the Peter Robinson department store before Burton bought it.
The building, which was completed in 1923, is listed as Grade II, with the listing noting its Portland stone cladding and its classical style with Beaux Arts details.