Adding to the positive sentiment, S&P Global’s flash UK PMI also showed the manufacturing sector enjoyed its fastest growth in more than two years.
Mr Williamson of S&P Global said the figures indicated that Britain “continues to recover from the mild recession seen late last year”.
He added: “The survey also brings welcome news of a cooling in service sector inflation, which is needed to open the door for the Bank of England to start cutting interest rates.”
However, fears that rate cuts may be delayed saw Barclays become the first high street bank to raise mortgage rates after Mr Sunak announced the July 4 poll.
The high street giant announced a 5.8pc increase on three-year fixes and said those remortgaging would pay an additional 0.25pc from Friday.
Other major lenders, including Santander, announced that their mortgage rates would be cut.
Santander will drop its five-year fix on a 60pc loan to value (LTV) from 4.5pc to 4.42pc, whereas its three-year fixes will fall by up to 0.26pc from Friday.
In a boost for prospective landlords, the bank’s buy-to-let rates will be cut by up to 0.2pc, with a two-year fix on a 75pc LTV to be priced at 4.96pc.
TSB will also cut rates from Friday. Its rates for first time buyers will drop by up to 0.40pc, and it will reintroduce two-year trackers for both new and existing mortgage customers.
Interest rates have been held at 5.25pc since last August, following 14 consecutive rises from December 2021.