That thomson seat post -although a bent one is an inline seat post. This means that the fixing of the saddle is central over the centre of the Post itself. The type of seat post you currently have is one of the old forms of post that uses a separate clamp piece between the post and the saddle- and yours is fitted the wrong way round so the saddle is too far forward. Easy way to set it up is with the clamp rearward of the post as in the picture of the white saddle. The black saddle is the type of post that I mean.This is termed Lay back- not lean back as the thomson is.

Advantage of having the lay back type of fixing as compared to the inline, is that the saddle can be pushed further back by around 1". Now over the way your saddle had been set up- by around 2 to 3".

http://www.merlincycles.co.uk/acatal...EATPOSTS_.html

The link will show the type of seatpost that can be got- but Not certain what length the Kalloy ones are from Merlins. Most Local Bike Shops (LBS) will carry this type of post and they are possible to get in 25.4 as most Raleighs use this size. I would suggest a 300mm length as you will have to raise the Seat a fair amount and you still want some stem remaining in the Seat post- Then again if it is TOO long- you can always cut it down.

Similar can be done to the Bar stem as you CAN get different lengths for height and reach but just change one thing at a time and get the saddle far enough back and high enough to start with.