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:
British Rail Class 97/6
Table title:
Fleet details
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=2 rowspan=1 > Number(s) </th><th colspan=1 rowspan=1 > Built </th><th colspan=1 rowspan=1 > Final livery </th><th colspan=1 rowspan=1 > Withdrawn </th><th colspan=1 rowspan=1 > Disposal </th><th colspan=1 rowspan=1 > Notes </th></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 97650 </td><td colspan=1 rowspan=1 > PWM650 </td><td class="highlighted"  colspan=1 rowspan=1 > 1953 </td><td colspan=1 rowspan=1 > BR Blue </td><td colspan=1 rowspan=1 > 1987 </td><td colspan=1 rowspan=1 > Preserved </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 97651 </td><td colspan=1 rowspan=1 > PWM651 </td><td class="highlighted"  colspan=1 rowspan=1 > 1959 </td><td colspan=1 rowspan=1 > CE Yellow </td><td colspan=1 rowspan=1 > 1996 </td><td colspan=1 rowspan=1 > Preserved - Swindon and Cricklade Railway </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 97652 </td><td colspan=1 rowspan=1 > PWM652 </td><td class="highlighted"  colspan=1 rowspan=1 > 1959 </td><td colspan=1 rowspan=1 > CE Yellow </td><td colspan=1 rowspan=1 > 1987 </td><td colspan=1 rowspan=1 > Scrapped (1990) </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 97653 </td><td colspan=1 rowspan=1 > PWM653 </td><td class="highlighted"  colspan=1 rowspan=1 > 1959 </td><td colspan=1 rowspan=1 > CE Yellow </td><td colspan=1 rowspan=1 > 1993 </td><td colspan=1 rowspan=1 > Scrapped (2011) </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 97654 </td><td colspan=1 rowspan=1 > PWM654 </td><td class="highlighted"  colspan=1 rowspan=1 > 1959 </td><td colspan=1 rowspan=1 > CE Yellow </td><td colspan=1 rowspan=1 > 2005 </td><td colspan=1 rowspan=1 > Preserved </td><td colspan=1 rowspan=1 >  </td></tr>
</table>
Question:
When were the British Rail Class 97/6 built?
Answer:
The British Rail Class 97/6 were built in 1953 (97650) and 1959 (97651-654).