Why oh why do we need HS2?

My opposition to HS2 is not a nimby reaction. I am more concerned about the vast cost to the taxpayer of something which we do not need.
As an MEP for the East Midlands, I live in Northampton and the first stage of HS2, London to Birmingham, will pass through the southern part of Northants.  The claim that it will shave 33 minutes off the London/Birmingham time is an illusion.
In writing to the secretary of state I pointed out that currently the fastest train, Euston to Birmingham, takes 82 minutes but stops 3 times.  Non-stop that would be around 76 minutes taking you right into Birmingham at New Street Station.  HS2 will go to a new station 10 minutes away from there.  So the claimed journey of 49 minutes to Birmingham by HS2 becomes effectively 59 minutes; £30 billion for a total saving of only 17 minutes against a non-stop on existing track.
It is claimed for HS2 that we must compete with Europe with its High Speed Trains. Distances there are much greater, so they need to compete with us and travel between their capitals and other cities more quickly. A map on the French TGV network website (equivalent to HS2) includes the UK up to just north of Birmingham.  It shows that Paris to Brest is nearly 3 times further than London/Birmingham, Bordeaux is further still, and Toulouse is a good 4 times further.
So a London businessman using current services will get to Birmingham quicker than his Paris counterpart getting to Bordeaux or Toulouse.
In response to my letters the Secretary of State said that HS2 is to be part of a network extending to Manchester and Leeds. True, but the material promoting HS2 concentrates on the claimed time from London to Birmingham, hence my comments. He did not respond to my observations that in fact the claimed saving of 49 minutes London to Birmingham is only actually 17 minutes.
Much is made of HS2 being non-stop but you don't have to be a fast train not to stop at intermediate stations.  You can do that with existing trains, they used to be called an "Express". A frequent express service from Euston to Birmingham would need a re-jig of the existing track; widening the permanent way and re-building bridges, just like extending motorways. Even with advanced signalling that would come at far less cost than a completely new rail line.
The Secretary of State said that High Speed Rail is used on the continent over comparatively short distances.  Nevertheless the map of the French TGV system clearly shows that the longer inter-city routes came first and the short distances later, many yet to be completed. So the distances from London outwards must be compared with similar continental routes.
I am convinced that HS2 is an unnecessary expense. We should use this money to up-grade existing track to run express non-stop services between major cities.