Cheers for the comments and feedback on your own experiences. In my parents' case, they forced open the front window with a crowbar. The window was old and was a weak point of entry, which the thieves exploited. I didn't even notice at first when I unlocked the front door and noticed the chain was put on from the inside. This was to give the thieves time to escape if they were disturbed whilst ransacking the place.
I managed to get into the house by unhooking the side gate, which was attached to the fence of the property next door, which is currently a building site. Questioned two of the labourers putting up bricks, but both denied seeing anything and said they only started at 8 am and work weekends. That means there are a number of other labourers and builders working the site during the week, who can see who comes in and out of the property and we have no idea who they are and what their background is.
Anyway, got round the back of the house and noticed through the kitchen window that the fridge and freezer doors, cupboard drawers were open and I knew that there had been a break-in. Then back patio door was open and I got into the house that way. Living room side cabinets and papers emptied. I then checked upstairs and they'd tipped everything from the drawers onto the beds. They've taken cash and jewellery. The first port of call for any thieves is to go for the bedrooms; so if you do hide anything of value make sure it's not in your bedrooms. Unfortunately, my parents of that generation to keep cash and jewellery there (this has obviously now got to change). It looked like a quick in and out job, as my parents' car was still in the garage. They weren't interested in the TVs, as too bulky to carry out.
I called 101 and reported it straight away and went downstairs to check the dining room and only then noticed the front window had been prized open with a crowbar and this is how they got entry to the house.
Anyway, spoke to the neighbours on the other side to my parents, as he was burgled 2 months previously. They smashed his back patio door to get entry and ransacked one of the bedrooms, but they say they must have disturbed them and they did a runner.
Anyway, just got to keep checking on my parents' house until they get back from holiday. I haven't told them yet, as did not want to ruin their holiday and they can't do much from where they are anyway. But it's gonna be a massive shock to them when they get back, but also a massive wake-up call to get CCTV and the place alarmed, secure the property properly because, with hindsight, it was really was an easy target. I can't contact their insurance anyway at this point and any assessor would want to speak to them directly.
The two officers who attended - one forensics and the other a PC have done their jobs now and now it is a case of the detectives to investigate, but I am not holding out much hope either and how much they will follow up on checking who is working next door on that building site. Just too much of a coincidence that since they started 6 months ago, two break-ins have occurred in the two adjacent properties.