I too am a descendant of Peter Haldane via Thomas Peter John Haldane (Peter Haldane the tailor's grandson).
When I was looking for Thomas Peter John Haldane's birth I couldn't find him in GRO records so I looked at baptismal registers for Chelsea as according to 1881 and 1871 census this was supposed to be where he was born.
I did come across the baptism of Jane Haldane, daughter of Peter & Esther Haldane. Address: Lawrence Street. Trade: Tailor. This was in the baptismal register of St. Luke, Chelsea on 25th July 1840 and the birth date was given as 13th July 1840. This was on page 249 and I was looking at the microfilm copies held at London Metropolitan Archives. I didn't look back before September 1837 as I was specifically looking for Thomas born between 1838-1841. For the record I have since found Thomas' baptism in the register of St. George, Hanover Square in 1838.
Can anyone claim Peter & Esther Haldane as their ancestors?