A set of carved ivory busts featuring Keighley's first MP -- Sir Isaac Holden -- and his family is to be auctioned at Sotheby's.

The six sculptures, which are from a private collection, dated from around 1870.

Bosses at the world-famous auction house anticipate strong interest in the lot, which is expected to fetch between £500 and £700 when it comes under the hammer later this month.

The set depicts Sir Isaac, his wife, Sarah, and two of his four children. The busts of each child are duplicated.

A Sotheby's spokesman says: "The sculptures came to us as part of a consignment from a private collection.

"They are not signed so we do not know who carved them, but the pieces are of lovely quality and are clearly the work of a very good mid-Victorian sculptor.

"It is a mystery why the set features just two of the children, and indeed why duplicates were produced of those two. Unfortunately, very little is known about the origins of the work."

Sir Isaac -- who was born into humble surroundings near Paisley, in Scotland -- was a textile magnate and founded, in Bradford, the world's largest wool-combing establishment.

He was also a Wesleyan, an inventor and in 1885 -- at the age of 78 -- became Keighley's first MP.

Sir Isaac held that post for the next 11 years.

He was behind the construction of the palatial Oakworth Hall -- at the heart of his wife's native village -- and it remained his home until his death in 1897.

The one-time grounds of the hall now form Holden Park, where a bust of Sir Isaac stands at the entrance.

The bust was returned to the park in March, 1999, after being restored by Bradford Museums as part of a major programme of repairs and improvements.

Sotheby's says that anyone interested in bidding at the auction -- at its West Sussex sale rooms on January 30 -- should phone 01403 833500.