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:
1921 Isle of Man TT
Table title:
Senior 500 cc Race
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=1 > Pos </th><th colspan=1 rowspan=1 > Rider </th><th colspan=1 rowspan=1 > Machine </th><th colspan=1 rowspan=1 > Time </th><th colspan=1 rowspan=1 > Speed </th><th colspan=1 rowspan=1 > Laps </th></tr>
<tr> <td colspan=1 rowspan=1 > 1 </td><td class="highlighted"  colspan=1 rowspan=1 > United Kingdom Howard R Davies </td><td colspan=1 rowspan=1 > AJS </td><td class="highlighted"  colspan=1 rowspan=1 > 4.09.22 </td><td class="highlighted"  colspan=1 rowspan=1 > 54.49 mph (87.69 km/h) </td><td colspan=1 rowspan=1 > 6 </td></tr>
<tr> <td colspan=1 rowspan=1 > 2 </td><td class="highlighted"  colspan=1 rowspan=1 > United Kingdom Freddie W Dixon </td><td colspan=1 rowspan=1 > Indian </td><td class="highlighted"  colspan=1 rowspan=1 > 4.11.25 </td><td colspan=1 rowspan=1 > 54.02 mph (86.94 km/h) </td><td colspan=1 rowspan=1 > 6 </td></tr>
<tr> <td colspan=1 rowspan=1 > 3 </td><td class="highlighted"  colspan=1 rowspan=1 > United Kingdom Bert le Vack </td><td colspan=1 rowspan=1 > Indian </td><td colspan=1 rowspan=1 > 4.12.06 </td><td colspan=1 rowspan=1 > 53.91 mph (86.76 km/h) </td><td colspan=1 rowspan=1 > 6 </td></tr>
</table>
Question:
Who won the 1921 Isle of Man TT Senior race and by how much compared to the second and third place?
Answer:
The 1921 Isle of Man TT Senior race was won by Howard Davies, by a margin of 2 minutes and 3 seconds from Freddie Dixon, and Bert Le Vack, in 4 hours, 9 minutes and 22 seconds, at a speed of 54.49 mph (87.69 km/h).