Locals say the area has been targeted by lead thieves in previous months.

Derbyshire Police tonight described the death as “unexplained” and officers
said they are keeping an “open mind” as attempts are made to identify the
victim.

The man’s body is believed to have been there for several weeks and is
understood to have been significantly decomposed, which attracted an
unusually high number of flies.

The body was removed late on Wednesday and a post mortem examination is due to
take place later.

Today, forensic teams continued working throughout the building, which was
formally the Court of Probate until it was closed in 1928.

The Daily Telegraph understands the painstaking recovery operation was
hampered by the building’s historic listing, forcing police to call in
specialists to take remove part of the chimney one brick at a time.

Builders were last month called in to investigate reported damage to the
premises and found a hole in the roof of the former 18th century town house.

After telling workers it appeared to be an attempted break-in, the incident
was forgotten until the appearance of the unusual smell. Staff were last
night said to be in shock over the “tragedy”.

A Derbyshire Police spokesman tonight said the death was being treated as
“unexplained”.

He added: “Officers were called to the business on St Mary’s Gate in
Derby city centre at around noon on Wednesday after the body, believed to be
that of a man, was found.

“The area was cordoned off while the body was removed. Officers are
working to establish the identity of the man and inform his family.”

The firm’s senior partner, Julie Marson, said that it appeared to be an
“awful” tragedy. She said: “It’s such a dreadful way for anybody to die,
regardless of what the chap was trying to do.”

St Mary’s Gate is an historic street in the city centre with buildings dating
back to the 1850s. It has traditionally been the legal quarter of the city
and is where the Magistrates Court is located.

According to the firm’s website, the building is one of the last in the city
centre to retain its old walled garden. It is located opposite the former
police station, built in 1893, which is now a luxury hotel having been
converted in 2006.