I wanted to extract -151557 and 6768743 from the below line. Don't know how can i do using regular expression.

These are mX and mY coordinates for a particular geographic location.
So any coordinate like number after string 'mX' will be mX
any coordinate like number after string 'mY' will be mY

which i want to extract

<div align="center"><center><table border="1" cellspacing="1" width="70%"><tr> <td width="50%" align="center" valign="middle"><strong>OS X</strong> </td> <td width="50%" align="center" valign="middle">443921 </td></tr><tr> <td width="50%" align="center" valign="middle"><strong>OS Y</strong> </td> <td width="50%" align="center" valign="middle">235124 </td></tr><tr> <td width="50%" align="center" valign="middle"><strong>Post Code</strong>
 </td> <td width="50%" align="center" valign="middle">OX15 4HE </td></tr><tr> <td width="50%" align="center" valign="middle"><strong>Lat</strong> (WGS84)  </td> <td width="50%" align="center" valign="middle">N52:00:46 ( 52.012814 ) </td></tr><tr> <td width="50%" align="center" valign="middle"><strong>Long</strong> (WGS84)  </td> <td width="50%" align="center" valign="middle">W1:21:41 ( -1.361467 ) </td></tr><tr> <td width="50%" align="center" valign="middle"><strong>LR</strong> </td>
 <td width="50%" align="center" valign="middle">SP439351 </td></tr><tr> <td width="50%" align="center" valign="middle"><strong>mX</strong> </td> <td width="50%" align="center" valign="middle">-151557</td></tr><tr> <td width="50%" align="center" valign="middle"><strong>mY</strong> </td> <td width="50%" align="center" valign="middle">6768743 </td></tr><tr> <td width="50%" align="center" valign="middle">
<strong>M</strong> </td> <td width="50%" align="center" valign="middle">Actual : FFFDAFFB_00674867<br>Street : FFFDB034_00674774<br>Road   : FFFDB610_00672640<br>Road64 : FFFE0C00_00668A00<br>Road128: FFFE0C00_00659000</td>
</tr><tr> <td width="100%" align="center" valign="middle" colspan="2" ><strong><a href="http://www.streetmap.co.uk/streetmap.dll?grid2map?X=443921&Y=235124&arrow=Y&adkey="~"">Click here to see location</a> </strong>

Try this:

$ sed 's/\<[^<]*\>//g;s/.*mX *\([-0-9]*\).*$/\1/' < string
-151557
$ sed 's/\<[^<]*\>//g;s/.*mY *\([-0-9]*\).*$/\1/' < string
6768743
$