Has Lord Ashcroft got a weight problem?

With great fanfare the latest Lord Ashcroft poll is out. and it shows the SNP sweeping thru the Scottish Nation. You can see Lord Ashcrofts thoughts HERE

Now weighting is a bug bear of mine, has to be done due to the amount of respondents you get and trying to get it to fit the demographic of the area you are getting the result for. BUT!

Does it also sway the result?

Labour had one bit of cheer from the result

Scottish Polling @LordAshcroft Aged 65+ voting intentions LAB 52% SNP 29% CON 13% UKIP 3% LD 2% GRN 1% The only bit of cheer for Labour
— General Election (@UKELECTIONS2015) February 4, 2015

The over 65s are going to be the most likely to vote it is accepted by everyone. Yet in Lord Ashcrofts poll he weights the respondents down in his survey for the over 65s from 28% of his actual respondents to 18% of the actual figures used. In other categories his polling has raised the share such as in the 18-24 section, they only got 5% of the actual respondents but after weighting that became 14% in this category the SNP had a 20% lead over Labour.

So has weighting affected the poll?

Hey if I am wrong I am wrong, and I bow to the greater knowledge out there but just wondered if this would have an effect.