user
Instruction
Answer the question based on the provided table.


Table
Table Title: '' regarding '1920 Rhondda West by-election'
Table Content:
| Party | Party | Candidate | Votes | % | ± |
| --- | --- | --- | --- | --- | --- |
| - | Labour | William John | 14,035 | 58.5 | N/A |
| C | Unionist | Gwilym Rowlands | 9,959 | 41.5 | N/A |
| Majority | Majority | Majority | 4,076 | 17.0 | N/A |
| Turnout | Turnout | Turnout | 23,949 | 70.2 | - |
| - | Labour hold | Labour hold | Swing | - | - |
| C indicates candidate endorsed by the coalition government. | C indicates candidate endorsed by the coalition government. | C indicates candidate endorsed by the coalition government. | C indicates candidate endorsed by the coalition government. | C indicates candidate endorsed by the coalition government. | C indicates candidate endorsed by the coalition government. |


Question
Who won the 1920 Rhondda West by-election  for which party, and by how many votes over which candidate?


Answer Format
The final answer should be a sentence and use the following format:
```json
{
    "answer": "your_generated_sentence_here"
}
```
rule
["The 1920 Rhondda West by-election result was a victory for the Labour candidate, William John, who won with a majority of 4,076 votes over Gwilym Rowlands."]