1) Compared to France and Germany the climate and environment is a lot simpler. We don't have lots of mountains with tunnels, the temperature barely dips below freezing. Even though we have roughly the same population size, we have roughly half the length of motorways [0].
2) In the 80s a lot of public infrastructure was privatised. Taking the railways as an example, First Group is a company listed on the London Stock Exchange which owns a large majority of train and local bus services across the country [1]. Infrastructure projects are still funded by the government, but they are often funded in the way of loans, that at some point they expect to be repaid, so don't impact the GDP.
3) After the financial crisis, fixed capital spending was greatly cut (as well as public spending in general), but as a % of GDP it still hasn't returned to its 2008 levels [2]. I suspect a lot of what was cut was really improvements and new projects that have been shelved. If we were to compare it to other countries over a greater timeframe, I'd expect to see the spending closer to that of France and Germany.
It'll be interesting to see what happens after Brexit as a large percentage of both the construction labour force and building supplies are imported from Europe.
[0] http://www.nationmaster.com/country-info/stats/Transport/Roa...
[1] https://en.m.wikipedia.org/wiki/FirstGroup
[2] https://tradingeconomics.com/united-kingdom/gross-fixed-capi...