Table:
0
A
B
C
D
E
1
Name
Builder
Type
Works Number
Built
2
Pioneer
Andrew Barclay & Co
0-4-0 WT (converted to 0-4-2 WT)
unknown
1876
3
Chevalier
Andrew Barclay & Co
0-4-0 ST (converted to 0-4-2 ST)
269
1885
4
Princess
Kerr Stuart
0-4-2 T
717
1900
5
Argyll
Andrew Barclay & Co
0-6-2 T
1049
1906
6
Atlantic
Andrew Barclay & Co
0-6-2 T
1098
1907

Questions and formulas:
Question: What is Name, when Builder is "Kerr Stuart"?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:E1,B1="kerr stuart"),1))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:E6,B2:B6="kerr stuart"),1))
Level: medium
Question: What is Built, when Works Number is "717"?
Formula: SUMIFS(E1,D1,"717")
Formula2: SUMIFS(E2:E6,D2:D6,"717")
Level: easy
Question: What is Type, when Works Number is "unknown"?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:E1,D1="unknown"),3))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:E6,D2:D6="unknown"),3))
Level: medium