Luxury home prices in London, the world’s most expensive city, may increase at a slower pace this year as more properties come onto a market with fewer buyers, real estate broker Knight Frank LLC said. The average price of London’s costliest houses and apartments probably will climb about 20 percent this year after an almost 29 percent gain in 2006, Knight Frank estimates. That would be the smallest gain since the 8.2 percent advance in 2005. (Bloomberg)