The National Horseracing Museum says that Son-in-Law is "probably the best and most distinguished stayer this country has ever known."

Described as "one of the principal influences for stamina in the modern thoroughbred" in Ulbrich's Peerage of Racehorses, Son-in-Law is seen in the pedigree of many of the top 100 show jumpers, particularly those of Holstein heritage.

In 1924 and 1930 Son-in-Law was the leading sire in Great Britain & Ireland. His progeny includes:

• Foxlaw (1922-1935) - won 1927 Ascot Gold Cup
• Straitlace (f. 1921) - won 1924 Epsom Oaks, Coronation Stakes
• Rustom Pasha - extremely important sire in Argentina
• Suzerain (f. 1933) - won 1937 Jockey Club Cup, Doncaster Cup
• Trimdon (f. 1926) - won 1931-32 Ascot Gold Cup

References

• Detailed profile of Son-in-Law at Thoroughbred Heritage
• Son-in-Law's pedigree and partial racing stats
• Son-in-Law's profile at the National Horseracing Museum, Newmarket
• Ulbrich's Peerage of Racehorses