You think UK will keep it after Brexit if EU doesn't? I doubt it. Australia has a strange situation where some states observe DST and some don't. (Or had 10 years ago anyhow)
But it will change, specifically: twice a year any UK-EU timezone offsets would change, affecting all communication and arrangements between UK and EU. Currently we are all in sync even though we are offset, so it might actually be more hassle to keep it DST if the EU does not.
It would change the time relative to Ireland, which is in the same timezone as the UK and has very close ties to it. It would introduce timezone differences along the Irish border. It would also change the time difference to every EU country twice a year; those differences are currently constant.
> So yeah, considering the amount of hassle it would be to change
What hassle would that be?
Given we couldn't even be bothered to move to a timezone that EU other countries are on (Portugal aside), I can't see there being much appetite for change.
Now, if the EU Commission had said they were forbidding the removal of daylight saving, I think it would be a completely different story...
And -the republic of- Ireland! A "timezone" border to be added to the one already introduced by Brexit
Legally, it is almost comical.
The Act of Parliament defining daylight savings time has a significantly different mechanism to how daylight savings time has operated in harmony with the E.U. for the past several decades. It allowed for double daylight savings time, ran over a different part of the year, and had to deal with Easter.
It was modified by an Order in Council in 2002, which removed double daylight savings time and changed the rules for the start and end. This was not the first time that the 1972 Summer Time Act had been modified by statutory instrument for harmonization with the E.U., either.
But that Order in Council was done by the Queen under the authority of the European Communities Act 1972, which is repealed by the European Union (Withdrawal) Act 2018. That, in turn, classes the Order in Council as "EU-derived domestic legislation". It retains it, but abolishes the Act that authorizes such orders. Adding to the comedy, the 2002 Order in Council also abolished the original authority to issue statutory instruments that was in the 1972 Summer Time Act itself.
So a different new mechanism has to be created to authorize further orders in council if the 1972 Summer Time Act is to be altered with another statutory instrument. There apparently isn't one in the E.U. Withdrawal Act 2018, by my reading, as "EU-derived domestic legislation" is not covered by the infamous so-called "Henry 8" provisions for dealing with "direct EU legislation". Otherwise and more likely, a full Act of Parliament has to be made to replace the (modified) 1972 Summer Time Act.
However, now look to history. There have been numerous attempts at this over the years, some fairly recent. They have got nowhere. The upshot of the legal tangle and the political will that effectively blocks changing the status quo is thus very likely that the U.K. will keep to the old E.U. rules after the E.U. itself abandons them. This is highly ironic for Brexit.
* http://www.legislation.gov.uk/ukpga/2018/16/crossheading/ret...
* http://www.legislation.gov.uk/uksi/2002/262/note/made
* http://www.legislation.gov.uk/uksi/2002/262/introduction/mad...
* http://www.legislation.gov.uk/ukpga/1972/6/section/1/enacted
* http://www.legislation.gov.uk/ukpga/1972/6/section/2/enacted
* http://www.legislation.gov.uk/ukpga/1972/6/section/2
* https://en.wikipedia.org/wiki/British_Summer_Time#Current_st...