costs serious money
BAE, RR, Babcock, Thales, Cobham etc have money. Maybe they just don't want to embarrass the government and would rather make as much as they can while they can from the shrinking pot and don't want to be seen to pressuring the government for more.
The most recent AA Populus poll (monthly thing which seeks opinions on mainly motoring/transport matters) asked participants to list the three issues which caused them most concern from a list of about 15 - the economy, welfare, Brexit, education, NHS, environment, transport, the usual stuff. Defence wasn't even an option!
Which perfectly illustrates why the defence lobby needs to get its act together. As HH says, maybe the Russians releasing nerve agents in the UK might do something . .