May 18 (Reuters) - UK's blue-chip FTSE 100 gained on

Monday, lifted by energy stocks tracking higher crude oil

prices, while the more domestically focused midcap index was

subdued amid concerns about inflation and Prime Minister Keir

Starmer's future.

The FTSE 100 ended 1.3% higher at 10,323.8 points,

while the FTSE 250 ended 0.07% lower after falling as

much 0.7% earlier in the day.

* Earlier in the day, Starmer's deputy said he would not set

out a timetable for his departure, defying calls to quit from

his party's lawmakers. Starmer said he remained focused on doing

his job.

* The prime minister has dug his heels in despite intense

pressure following a set of poor local election results earlier

this month.

* Last week, Greater Manchester Mayor Andy Burnham said he

would seek ​to contest a parliamentary seat becoming vacant

after a colleague decided to stand down, paving the way for him

to challenge Starmer for the Labour leadership.

* Investors are concerned that Burnham could usher in a

period of more government spending ​and borrowing, straining

Britain's already stretched public finances.

* "The political centre of gravity is likely to shift left.

And yes, there is pressure to adapt the fiscal rules. But

politicians across the spectrum are presumably acutely aware

there are limits," said James Smith, developed markets

economist, UK, at ING.

* With shipping through the Strait of Hormuz still

disrupted, inflation worries have gripped markets, particularly

as oil prices stay elevated.

* Brent crude futures rose 1.6% as worries over

supply disruption from the Iran war offset a report the U.S. had

accepted temporarily waiving sanctions on Iranian crude. Energy

stocks rose 2.9%.

* Homebuilder stocks dropped 0.5%. Asking

prices for British homes in May rose by more than usual for the

time of year, property website Rightmove said.

* Bank stocks climbed 1% as the finance

​ministry laid out planned changes ‌to ring-fencing rules, which

it said ​would create a "more ​agile and proportionate regime".