Please read the following table in HTML format from a webpage and then answer the question in detail according to the table. Each table cell is defined by a <td> and a </td> tag. Each table row starts with a <tr> and ends with a </tr> tag. 'rowspan=m' and 'colspan=n' represents a cell spaning over 'm' rows and 'n' columns.

Webpage title:
Derby South (UK Parliament constituency)
Table title:
Elections in the 1980s
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=2 rowspan=1 > Party </th><th colspan=1 rowspan=1 > Candidate </th><th colspan=1 rowspan=1 > Votes </th><th colspan=1 rowspan=1 > % </th><th colspan=1 rowspan=1 > ± </th></tr>
<tr> <td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 > Labour </td><td class="highlighted"  colspan=1 rowspan=1 > Margaret Beckett </td><td colspan=1 rowspan=1 > 18,169 </td><td colspan=1 rowspan=1 > 39.3 </td><td colspan=1 rowspan=1 > −10.7 </td></tr>
<tr> <td colspan=1 rowspan=1 >  </td><td class="highlighted"  colspan=1 rowspan=1 > Conservative </td><td colspan=1 rowspan=1 > G.W. Hales </td><td colspan=1 rowspan=1 > 17,748 </td><td colspan=1 rowspan=1 > 38.4 </td><td colspan=1 rowspan=1 > −0.3 </td></tr>
<tr> <td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 > Social Democratic </td><td colspan=1 rowspan=1 > I.W. Smith </td><td colspan=1 rowspan=1 > 9,976 </td><td colspan=1 rowspan=1 > 21.6 </td><td colspan=1 rowspan=1 > +11.9 </td></tr>
<tr> <td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 > Ecology </td><td colspan=1 rowspan=1 > E. Wall </td><td colspan=1 rowspan=1 > 297 </td><td colspan=1 rowspan=1 > 0.7 </td><td colspan=1 rowspan=1 > N/A </td></tr>
<tr> <th colspan=3 rowspan=1 > Majority </th><td class="highlighted"  colspan=1 rowspan=1 > 421 </td><td colspan=1 rowspan=1 > 0.9 </td><td colspan=1 rowspan=1 > −10.4 </td></tr>
<tr> <th colspan=3 rowspan=1 > Turnout </th><td colspan=1 rowspan=1 > 46,190 </td><td colspan=1 rowspan=1 > 67.4 </td><td colspan=1 rowspan=1 > −4.0 </td></tr>
<tr> <td colspan=1 rowspan=1 >  </td><td colspan=2 rowspan=1 > Labour hold </td><th colspan=1 rowspan=1 > Swing </th><td colspan=1 rowspan=1 >  </td><td colspan=1 rowspan=1 >  </td></tr>
</table>
Question:
By how many votes did Beckett win the Derby South (UK Parliament constituency) election over the Conservative party?
Answer:
In the Derby South (UK Parliament constituency) election, Beckett won with a majority of 421 over the Conservative Party.